Can you ever get perfect alignment?

Of course we can't get perfect alignment but we can get it very close.

Usually the best alignment protractors are the ones supplied by the turntable manufacturer because they know how to line up the arcs and null points relative to the tonearm pivot axis.  
I agree about universal gauges that ask you to align to the pivot point by sight-it is introducing the chance for greater error.  
The mint "best tractor" has worked and sounded the best for me and my table (technics) given that the results with the supplied gauge were not optimum.  
In your case trying to align short cantilever (dynavector?)  i would suggest adding some local stationary lighting and magnification (e.g. a 3-piece magnifying optic) to make it easier to see.  
even though we can never get it perfect we can get close and careful setup work does pay dividends in sound quality. 
you'll know when it's right when most of your LPs sound great from outer to inner grooves.  

Of course you can get a perfect alignment. With some carts it is easy (carts with naked cantilever for example) and with others it will need time. Take care that "it" will fit perfectly onto your spindle (they can have different diameters)...
The Graham Phantom Arm for example has a alignment jig and you can do it perfectly even with 10 left thumbs.

So far we have one "of course we can't" and one "of course you can".  
I know we may be able to get a cart perfectly lined up with a gauge, but is the gauge lined up? 

I tend to do a mildly modified baerwald, where the leadout is slightly cleaner. This tends to be the place where wear is most noticeable, IMO.

the reason I say we can’t get it perfect is because every form of alignment has only (2) points on the side of an album where the stylus is perfectly tangential to the grooves of an LP (unless you have a tangential / linear tracking turntable)
even a "perfect" alignment to a given formula is still perfect in just (2) spots- and the alignmant of the rest of the tonearm arc is a compromise.

@avanti1960 Thank you, you have nailed it!

Actually you have three dimensional space in which a cartridge is aligned.
You can get it about right with care but the record you are playing
changes the plane constantly because no record surface is perfectly flat. That is why I use a unipivot arm to compensate for this factor. The ability of the stylus to tract well is also a factor in both vertical and lateral imperfections. 

I can get darn close to makeing me happy, my ears are the final judge.

I use the Kuzma Airline (linear tracker). I don’t know that any third party protractors or other alignment tools (apart, perhaps from azimuth) would be useful- the arm comes with a simple gloss cardboard ’card’ with appropriate markings. I use a magnifying glass to get the points on the alignment card to the center of the stylus, as much as I am able to see that with modest magnification. There are two marks, like "null points" but given the straight line tracking, these don’t describe part of an arc, as with conventional pivoted arms.
The greatest difficulty is moving the very heavy arm pod (Kuzma XL) to get the arm into position. It can be time consuming, and even though the simple cardboard jig doesn’t seem particularly sophisticated, there is a big difference in result between "close enough" and "spot on" (or at least as "spot on" as I can make it, in light of the equipment involved).
The additional trick with this arm is that it is supposed to be level, but at a slightest cant inward toward the spindle-- "too level" may result in the stylus hanging up on a groove.
Although I used to view this process with trepidation, I have owned the arm a long time and am now pretty good at setting it up.
Adding a Minus K anti-vibration platform beneath the table/arm assembly required additional jiggering-- since the table has no real center of mass to balance the load, and requires a balance between the center of the table and heavy arm pod for the Minus K top platform to be level. (I use an HRS platform between the Minus K top and the turntable-- so it is a lot of physical work to get the table in place just to start the set up process).

avanti1960mthe reason I say we can’t get it perfect is because every form of alignment has only (2) points on the side of an album where the stylus is perfectly tangential to the grooves ...

If you can achieve tangency at those two null points, that's as "perfect" as you can get. But if you align the cartridge body rather than the stylus/cantilever assembly by using a mirrored gauge, it's likely that you haven't achieved tangency even at the null points.

I have always found the two points on the tonearm arc an interesting phenomena. In a dialed-in system kit, room, if one is in audiophile mode, you can hear when the stylus crosses these points. the focus gets dialed in. The records grooves are the smallest, and the revolutions faster as the tonearm/cartridge approaches the spindle. This makes it harder to track the inner grooves of a record. It therefore makes sense to set up the tonearm to try to ensure one of these points are closer to the spindle.

Another phenomena some are not aware of with the pivot tonearm. Look at the shape of the tonearm arc on your alignment tool. It is obvious that the tonearm/cart runs at different speeds. Faster up to midpoint - then slowing down after that.

Its impossible to set this up, so I am forced to talk the dreaded audio theory here, but, if there was a race with the linear tracker, and the pivot arm was set up on the outside, it would eventually end up overtaking the linear tracker, and the pivot arm would finish up on the inside.
So even if the turntable runs at a stable true 33.3, the tonearm does not.

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whart
The additional trick with this arm is that it is supposed to be level, but at a slightest cant inward toward the spindle-- "too level" may result in the stylus hanging up on a groove.

whart - I know a couple of owners that own the Kuzma Airline and the ET2. They confirm your findings. The ET2 has a very smooth bearing (slippery in comparison to the Kuzma). It needs to be level and will not get hung up. However if it is not level, it will affect the set up. The ET2 has a larger surface area, stationary manifold. The Kuzma's is smaller and moving. Two very different designs.