In my observations the length limitations, when posted, are usually 18 - 22ft marks ... then from there things open up or limit depending on how you look at it... to around the 30ft length area. When I had a 24ft TT I fit in spots that were listed for a few feet shorter RV's when allowed to try.
There's a difference between 5r & TT's fit lengths, trade-offs either way... I say shorter the better! ... I've a narrow body 21ft TH that I've had within inches of rock walls and drop offs getting to/from camp destinations. My spots are not camp grounds and in these types of areas, length really becomes an issue such as when you meet another vehicle and one of you has to back up a mile or more to find a spot where both can pass! Or you drive in a couple miles on a 1 lane trail to a favorite spot and find somebody already there and no place to turn around as the only open space is occupied!
Thoughts…
O- Understand the CCC’s as mfg docs sometimes claim 2300 or so pounds of capacity but not always clear is that water, LP, beer and all RV options come out of that mfg’s CCC. Let’s just say that 2klb is not much capacity when regular RV fluids & options get included. Get the tire upgrade if possible!
O- Water tanks can become a real issue if you boon-dock with a family for more than a couple days when everybody isn’t water conscious. Longer RV’s generally have bigger tanks! Though my 21ft’r has 100gal so these days that correlation or assumption is less valid.
O- Longer lengths require taller ground clearances to traverse less than level terrain. So, all is a trade-off … how far into the boondocks might you want to go? Do you mind camping with other people? How many must you sleep?
O-Suspension types might be a consideration … not to start a debate but if some lift is desired to keep the tail out of the dirt … leaf springs do axle over conversions quite effective both in results and cost. IMO, are better on rough dirt road travel too.
The list goes on!!! …