Okay, I have frozen pipes??

Replace the return air grill on the furnace with twin window fans. That keeps some warm cabin air circulating at all times.

As for unthawing, a radiant heater may be the best--the type with tubes which glow cherry red, with a reflector. They heat the object they are pointed at, rather than heating the air.

If your water is frozen then you might have some cracked pipes too. I had an old camper and the pipes froze one Winter. When they thawed I had water pouring all over. Be careful. It was a MH with a basement, 1988. I had a bulb in the basement to keep it warm and it worked to keep things from freezing until one night when the bulb went out. On the newer RVs they have the Furnace ducting from propane to keep the basement warm and pipes from freezing. I also keep cabinets open. On the outside, use heat tape and foam insulation. So far my 2012 5er has had no issues.

or wait another day or so. A heat wave is coming!

you gotta get some hot air moving.

If your water is all frozen, I mean both hot and cold to all faucets and if you have a compartment that houses all of your connections I would guess that your frozen spot would be right behind that door. If you think about it your plumbing is only 1/2 inch of styrofoam away from -7 degrees.
I know these RV folks say they build a four season unit but most of them recommend you not use it in below freezing conditions.
That being said , if you can determine where it is frozen you can take steps to prevent future problems.
Good Luck

PEX is less apt to be damaged.
Is there a furnace vent in the wet compartment? Make sure it is on.