Great sounding close to back wall speakers.

Having a front or rear port location doesn't matter once you get more than a few inches out from the wall.

Within the ports operating range the sound waves are _very_ long (28 feet at 40Hz), wrap arround the speaker like it wasn't there, and the speaker isn't at all directional.

Except for dipoles, horns, and cardioids all speakers are going to have a substantial (like 5dB) bass boost below 70Hz when placed within 2' of the wall.

I find that objectionable; if you do too you'll want either a speaker specifically _designed_ for on or in-wall placement or a parametric equalizer with a shelving high-pass filter.

Smaller Dunlavy (SC-IV or smaller) or Duntech (Princess or smaller) speakers will work OK as you mention, you'll lose a little depth and might get a bit more bass than otherwise specified in the measurements but otherwise you can be OK. The best close to wall speakers I have ever heard are the Snell Type A-IIIs, designed to be placed up against the wall and terrific speakers. I think there's a used pair up for sale on the 'gon now. Particularly good with classical music, and good bass extension. Only problem is that they're no longer in production, don't know about how well they can be serviced/repaired.

Have you checking into the Allison speakers which are designed go into corners and against a wall literally. One of their models was reviewed in TAS last year I believe.

My Eggleston Works Fontaines sound awesome at less than 24" from the wall (to the back of the speaker). But you'd have to find a pair used for your budget.