We are going to transition from a TC to either a TT or 5th wheel, leaning toward a TT so we would still have use of truck bed. We've traveled around most of the western states in the TC and no problem...
We went form a 26'tt to a 34'tt. Wished we had stayed smaller and will go back once kids are a bit older. We are much more restricted to where we fit now.
I would try to keep it under 28' and you should have no problems anywhere. Coming from a TC you should find that cavernous in comparison.