Very familiar with Scott tuners, and yes, it's a problem using better cables on them.
IMHO, right angle extensions may also be to large, especially the better ones, and even the cheap adapters tend to be larger than cheap RCA cables due to the nature of the construction.
Not easy to find, but some better cables used a slender RCA, like the original Audience Conductor. I have a friend that uses these on a Scott tuner with no problem.