I am considering a multi-day trip that would include 5 nights where temperatures get down to low 20s, high teens. During the day it will probably be more around 40s and 50s. We will be dry-camping or boondocking, but will have a generator we can run during the day to recharge the battery. We have pugs for the bunkends and dinette. Assuming we did reflectix and thick curtains in the windows, what temperature can I expect the onboard furnace to be able to maintain overnight? We aren't super "rough-it" types and really like to be comfortable. Plus we'll have our kids with us. I'm trying to figure out if this is feasible or if we should abandon this trip idea or suck it up and stay in rv parks with electric so we can have space heaters too.