A Roadtrek (depending on model) could certainly tow a trailer behind with your "toys" as long as you don't exceed the weight limit (which includes the weight of the Roadtrek). I know of several RT owners who tow a travel trialer behind. But a golf cart, etc. is really adding a lot of weight into a trailer to tow with a B. And, I am not sure what advantage you are going to get from a Class B if you want (need) to tow a utility trailer behind. You will lose the gas mpg advantage. You are just as big on the road with the trailer attached. You could as easily get a toy hauler TT and when you get to where you are going take off to tour in your tow vehicle. The advantage of a B is that you can go anywhere (kind of) - but not really with a trailer towed behind.
ALSO - Traveling with three in a Class B. It is tight with two. There is ZERO privacy. No room to walk around. There is an aisle that is six feet long by 28" wide. That and the seats in front and bed in back is the living space in my Roadtrek. For the two of us, it is tolerable as long as we are both in good moods. It takes a very close couple with extreme patience and understanding to travel in a B. Add in a teen and lots of luck.