My trailer came with two heat pumps and I only ever use them in "cool" mode because they are much louder than the furnace. I would not recommend them.
I believe your Tradewind is new enough that it would have the standard 14x14" roof mount opening, which would allow you to replace it with a modern A/C. The low-profile Dometic Penguin in 15,000 BTU would be the best choice. Any smaller won't cool your trailer sufficiently, and other makes and models don't have the condensate drain hose and will stain the outside of the trailer as condensate drips down the sides.
If you don't have a 14x14 open, but rather the two small holes, one for the fan shaft and one for refrigerant lines, you're better off fixing your existing A/C because of the hassle of switching everything around. It's easy to tell which situation you're in by removing the indoor air distribution box on the ceiling. If there's a fan and coils visible, you have the old setup and fixing is your best bet. If there's just ducts going up to the roof and some wires and control boxes, you have the 14x14 setup. Post a photo if you're not sure.
You should plan on replacing the propane heater if it doesn't work. You'll need it on cold mornings in the hill country.