To the OP - the temperature when you get up INSIDE the RV is what's important!
I remember as a kid in Michigan waking up in the morning with snow on the INSIDE of the sill of the window next to my bed in a radically under-heated bedroom. When I left Michigan I vowed that I'd never live like than again - including when camping.
No matter what the outside temp might drop down to, we always sleep in our rig with the propane furnace set at around 62-65 degrees. Nice to get up in the middle of the night to and to get up for breakfast to. ;)