U-Haul definitely rents one-way, as do most car rental companies (for the SUV option). You will definitely pay more than a local rental, since in theory, they need to return the vehicle when you're done. You'll use much less gas with an SUV. You should make sure the rental place allows towing (in case of an accident).

As for the mast behind the U-Haul, that's no big deal. You just need to handle it like we do with RVs. Place the mast into the cradles such that the mast stops at least 8 inches behind the hitch mechanism of the trailer. It depends on how much the hitch ball on the truck sticks out, you just want to be sure that as you go over bumps, into driveways, etc. that the mast doesn't contact the truck.

Of course, the mast will extend several extra feet behind the rear of the trailer than you're used to. Technically, you need to have a light on it if it's so many feet past the trailer lights, but most of us just use a red flag, etc. on the end of the mast.

Hope this helps.

Mike