One additional note on the wiring: If your car has a 4-prong flat, and the trailer has a 7-blade round (or maybe even a 6-pin round), I wasn't able to find a ready-made adapter to go in that direction -- they all went the other way.
I called a trailer shop and they said yep, that's how it is. They made me one from parts and wire for $17. I guess it's because that arrangement is "downgrading" the capability from the trailer to the vehicle, and they figure people won't be doing that.
(The larger connecter on the trailer can be for charging the trailer battery/running fridge
in trailer and/or for trailer brakes
- both of which your car can interface with if it's set up that way. In my case the larger connector on the trailer was only for running the fridge
, so it was no problem to go without that capability.)