26-1/2' ball to bumper for us.
You really need to look at floorplans and how much storage is available, DW liked the storage and bathroom layout in the NT we ended up with. A lot of cg's we go to from our pop-up days max out at 30'.
We've done a week of camping with just the 2 of us. But we really don't spend a lot of time in the TT, we use it as a "base camp" and are gone a lot of the time.
There are a lot of floorplans in the 30' range if you want to stretch yourself out. But then again, overall length will be close to what you have now.
2017 Grand Design Imagine 2650RK
2019 F250 XLT Supercab
Just DW & me......