moisture of door frames

In the summer I sweat...In the winter my door frames and windows sweat.

Aluminum is an excellent thermal conductor. If you had an infrared gun, you'd find the temp. of the frame relatively cold compared to the inside. The moist warm interior air will condense on the cold frame. About all you can do is use a dehumidifier or crack a window or roof vent open a little. You'll probably be seeing some condensation on window frames and glass too.

It is condensation caused by the humidity inside the trailer collecting on the cold door frame. There is not much you can do about it other than limit your cooking, especially steaming foods, and limit the use of hot water. The moisture also comes from your body and breath. You could try a dehumidifier, but I doubt you'll find the results worth the expense.

Probably not much you can do. It's the same thing that makes condensation form on the outside of a pop can in hot weather.
You could check to make sure the door is sealing against the weather strip. All it takes is an adjustment to the striker plate to make it seat better.