Having a 2006 Tioga 26Q I may be of some help.On mine the tanks are not heated or insulated.
Having had it in cold weather,20 Degree/40 Degree days it was a chore to keep it warm,it is not insulated well at all. I had no freezing of water lines for the days that I was there.
One thing nice is the 2 6 volt batteries located under the step did get me thru the night with the heater running.
One thing about the heater is that the vent closest to the heater is in the bathroom,I had to put an adjustable register there to cut it down some and put more hot air to the rear bedroom. Having the fresh water tank located under the dinette seat,inside the cabin where it was kept warm is a plus in cold weather.
Anything else I can be of help regarding this RV just ask,send a PM or
ask here I would be happy to help.
2006 TIOGA 26Q CHEVY 6.0 WORKHORSE VORTECFormer El Monte RV RentalRetired Teamster Local 692Buying A Rental Class C