I just scanned this post and replies, so sorry if I repeat info. But ya... effective top tube length is different than just standard TT length. It takes slope into account.
Surlys are just burly bikes, I find them to feel way too big. I had to sell them for a while and I didn't like it because I'm just not into their geometry.

Anyway... have you tried getting a zero offset seat post? That made a MAJOR difference for me when I've had similar issues. I found myself pushing the seat all the way back with the zero offset because I felt too close after a while. If your stand over feels good but the stretch is just too much, I'd try that before getting a new frame. and you don't have to get an expensive Thompson. Look on ebay... there are loads of different 27.2 seat posts.

It is also true that your back and neck muscles will strengthen up after a while and you may find being stretched out to be preferable in time. Or the tt just may be way too long.