as was said, a motorhome for full-timing, is normally better for couples and not families.
plus you seem to have left out a toad, a tow vehicle to drive around in.
then you have to deal with TWO motorized vehicles.
with a truck and 5th wheel, you only have have one to worry about.
lastly, you seriously need to rent something first, before you subject your family, especially teens, to a full-time lifestyle.
and don't think that you'll be saving lots of money, cause you won't.
RVing isn't cheap, especially full-timing.