I disagree with the post by jyrostng. I love how my 42 foot motorhome handles and we will do the 1500 miles to Colorado in two days. I go into shopping centers with it and whatever gas station has the cheapest diesel. In three months out West we will put over 7000 miles on the motor home and that many in the car when it's not attached to the motorhome.
There is another post today titled length restrictions that you should read.
There is a lot of truth to the saying about retirement where you have twice the husband on one half the income and in 1/10th the space if it is a 40 foot motorhome otherwise it could be 1/15th the space.
For FT you need plenty of CCC and that's hard to find in a shorter motorhome.