$3500 for the trailer PBR posted seems like a helluva deal to me.

I've loaded B-bodies (which are about 17' long) into 20' and 24' enclosed trailers:
They fit fine, but tying down the front in a 20' is tight and demands more agility, and is really tight for big guys.
The other deal is the 24' allows more positioning to center vehicle weight.
20' is lighter, requires less storage space, 24' is better @ resale.
Different people prioritize different things, so there's not really a right/wrong answer if the size hits one's targets.