Class A length
Where are you going? I would get a subscription to Motorhome Magazine and join FMCA to get there magazine also. Not a salesman for them but they do have some nice articles periodically about length.
Our Southwind is 37' with two slides. Just happened that was the size we bought. Liked the floor plan also but hate the "J" couch in the living room. Most uncomfortable piece of furniture we have sat on. And having guest sleep on it is a real joke. Going to get rid of it and put in a nice hide a bed. The "J" couch did look nice when we bought the rig though.
Some campgrounds limit the size of the rigs. Naturally, the longer the rig the harder it is to manuever in tight spaces. Going around the mountains will not be very much fun if you spend half your time on the other side of the road to keep from hitting guard rails.
And the weight thing is an issue too. Some manufacturers push the limits when they build the coach and don't leave much room for what the owners are going to bring with them. They don't take into consideration the weight of water, gasoline or diesel fuel, fresh water, or waste water. It is not a good idea to overload the rig.
Plus if you are going to pull a dinghy make sure you have an auxiliary braking unit in your dinghy. Most states have a weight restriction on towed vehicles or trailers and if you have an accident, even if it is not your fault, you can still be ticketed for unsafe towing. Your insurance company would have a real ball with that one.