He's going to be LIVING in it, so he will probably need to have water, not antifreeze.
It's according to where you are going to be living. If you are in the south where temps rarely get below 32 for more than a few hours, you should be fine, but will probably burn through lots of LP. If you are going to be where temps can be below freezing for days, you have lots to do.
1. Heat tape for incoming waterline.
2. Some type of windbreak for the underneath....some use the 1/2" styrofoam insulation.
3. Some type of heat source UNDER the trailer to keep things from freezing (100 watt light bulb)
4. Keeping the cabinets open to allow heat to get inside them.
5. Electric blanket for your bed.
6. Electric heaters to supplement the LP.
That's all I can think of right now, but I am sure others will chime in that have done it.
2017 Ford F350 Crew Cab 6.7L 4x4 DRW