The choice of TT length often has little to do with towing and parking so much as its intended use.
I got along fine with a PUP until I decided to retire. Then we decide to travel a lot. For us 25 ft. was optimum, not too big not too small.
While in FL we stopped at fishing and golf oriented parks with 30+ footers parked for months at a time, some even sporting flower boxes. :) In AZ we saw several that looked to be permanent with porches and concrete block supports. Towing and parking were of little concern.
On the other hand I have seen a few 30+ 5vers at the campground. The folks just liked the room when they camped. They also were very found of pull through sights. :)