2wheelluge - The average tent does not leak during a rain. Take a look around before you set up the tent (slight slope to drain the run-off and not puddle, not at the bottom of the hill where a lake might develop). :B
As to winterizing - a motorhome versus a trailer is not much different.
1. Drain the fresh tank, the water heater, the black, and gray tanks.
2. Set up the valves on the water heater to by-pass the heater as you do not want to waste RV antifreeze by filling the water heater.
3. Then pump the RV antifreeze in the water lines first to the farthest faucet (both hot and cold), and the toilet (run until a nice pink color).
4. Catch a bit of the antifreeze and pour in the shower drain.
5. Make sure the coach battery is disconnected from load (Store mode versus Use).
I do not do anything special to the chassis either fuel or battery wise. I try to visit the RV about every 4-6 weeks. While there, I bring a packet of pop-corn and an electric space heater. I fire up the generator for about 1/2 to 1 hour and depending on the weather will either use the microwave or the heater for a small load on the generator.