I did a few winters with temps in the single digits a few nights.
I made my own heated hose with a standard RV white water hose, heat tape, pipe insulation and electrical tape. I determined the length needed, bought a heat tape a couple feet longer. I then bought a splice kit for the hose and a new end, cut the hose to the length needed, put the tape along the length of the hose with a wrap of electrical tape every foot or so, then put the pipe wrap around the hose and tape once more securing with electrical tape. The excess heat tape on the female end I wrapped around the end of the faucet and covered all of the connection with insulation then put a empty 5 gallon bucket over it.
On the end connected to the trailer I put the other excess length to use wrapping it around the connection to the RV, pushed a piece of insulation in the compartment and closed the door with. This worked for me for 3 winters using same heat tape. I did replace the hose after the second winter.
I also skirted around the bottom, I bought the bi-fold foam board made to go behind vinyl siding, used 1x2 lumber secured to the ground with gutter spikes, screwed an upper piece of 1x2 to the bottom of the trailer, cut the foam to the right height and stapled top and bottom and taped the seams, it did make a big difference in keeping the floor warmed.
I also had a 100 gallon propane tank that the gas company filled for me prior to winter, I used an average one gallon per day by supplementing my heat with 1500 watt ceramic heaters.
Chris & Dianne
Jayco Designer 3110 SOLD 6-11-2016, looking for the next one.
F250 PSD 4x4 Crew Cab