I have an Avenger 28BHS...which is 31.5' tip to tail and we often have limitations due to length. It's not cumbersome to tow, but it simply too big for parks designed 30-60 years ago.
If you're adventurous, good at backing, and willing to leave if things don't work out, you can reserve small sights and see if you can squeeze in. We've done that and never had to leave, but I've been lucky....there have often been nearby sites listed as the same (short) length as the one we've reserved that there's no way we'd get into them.
I'd suggest 24' box / 26-27' tip to tail as the maximum size for flexibility.
