Any question answered...

When my seattube was to narrow from being overtightened, it wasn't properly round.

Maybe check it with calipers. If left to right (as in your picture) it's narrower than back to front, then it sounds like it's over tightening.

Thanks, good idea. Now I need calipers. And no, Dammit, I am not riding up your hill with a bike on my bike. ; )