You may want to consider tossing a tarp over the roof, while you work or live inside, until you can get the roof finished.
I also agree that you should consider keeping the LP appliances, if they work....and even consider having them repaired/cleaned, as it would still be less expensive than new appliances.
You will want the water heater first.....as you can cook on a grill or a microwave. The lighting will be 12VDC, so you want the converter working for that, though you can get away with just hooking up a new battery and a battery charger (charging every few days, as needed) until you have the money to invest in a inverter/converter for the unit.
If you have no intentions of moving the unit, you might want to just put in some 110VAC lights, and forget about the 12VDC.....but, if you want to sell it later on, you'll want it to be a Travel Trailer, and more than likely, most of the 12VDC stuff should be OK. Also, things like the water pump, and alarms are 12VDC, so you probably should keep that system intact.:)
You didn't mention where you live, so I don't know if your water lines would have been effected by winter freezing, so that is something you will want to check also. The water heater may also be split, or at the least, have bad connections.
I would get a water line fitting that you can hook an air-line to (you can get them at Walmart in the RV section), and have someone hook up about 40 psi air to the system, and listen for leaks.....if you hear air, you would see water if the water was connected. Air is less damaging:B
The small A/C unit is something that a lot of people have done. You may also want to get a Dorm fridge, which would be 110VAC, but easier to use than the LP units, and chances are, your unit is probably shot anyway.
Power wise, you are looking at having at least 30A service to your trailer, if you are going to use the original shore connection plug. Please be aware that this is NOT the same plug that the clothes dryer plugs into. This needs a 30A 110VAC outlet....especially if you are going to have A/C and a microwave. If you were to go with an electric water heater,you might have to run a second power source for it, as most RVs don't have the electric heaters.
As mentioned, there is a plethora of information on this forum, and lots of folks with wonderful information and the willingness to help you.
I would suggest pictures....we love pictures...and it gives folks an idea of what you are trying to tackle. Some may say that it's not worth your time or money, depending on the age of the trailer, and the condition.....you may just be sinking money into a black hole!:(
Good luck
Bill & Claudia / DD Jenn / DS Chris / GS MJDogs: Sophie, Abby, Brandy, Kahlie, Annie, Maggie, Tugger & Beau 🙂RIP: Cookie, Foxy & Gidget @ Rainbow Bridge.😞2000 Winnebago "Minnie" 31C, Ford V-10
Purchased April 2008:B FMCA# F407293
The Pets