Enclosed trailer purchase!

For you more intelligent fellas, I want to add a winch to my new trailer. Someone else was talking about winch ratings. Say for a 3500# car, what rating of winch would suffice?
Also, should I install a battery and a little solar panel or just hook it up via the truck electric? I can’t ever see where I would be loading a car with the trailer unhooked so I don’t THINk I would need a battery. I do however think a remote would be really handy because it’s so often I have to do things solo.