Ron: I do have my jeep liberty set up for towing, however I would rather not tow that if I could. This trip is going to be 3 weeks and a few days and a lot of our stops are going to be hit and go, so I think I can do with out the toad. Besides it will save on fuel. David
With our 2007 2350 towing our Jeep Liberty 4000 miles from Chicago to Jasper Alberta and back at around 70mph, we averaged 9.2mpg. You towing the same, should see better if you slow down to 60-65mph max, even considering the extra weight of 4 people.
Leaving your Liberty home will force you to drive the PC 100% of the time. Your average fuel economy will drop like a tank given every move will be on roads less than ideal for a motor home. Between all the steep grades, very slow winding curves at various speed, and even some traffic, you'll be doing worse over-all compared to the fuel lost in towing your Liberty. Your kids won't see much either from the "limited view" of the PC windows. I advise to tow the Liberty to benefit of storage, mobiity, child sight-seeing views, and combined fuel savings. Not fuel loss.
We do on-the-go vacationing all the time, often staying in places a night or two, so I understand your comment of "hit and go". But the tow vehicle "STILL" makes it work so much better. Your first primitive road with limited vehicle length and you'll be saying...."Why did we leave the Liberty home?" Also your kids will be saying....."What Buffalo? We can't see anything from back here!"
Regardless of your decision, keep close track of your fuel consumption averaged from the entire trip and see how you did. You only need to write down the starting odometer reading at home with a full tank of gas, write down the gallons to the 10th gallon purchased thereafter. Then once back home, fill up one last time and right down the mileage again. Calculate from there. It wil provide an extremely accuate figure.