It is easier to by a large/expensive RV when you own something else. Banks are more willing to lend you money. Also, if you look around, you will see that 'fulltimer' interest rates are often higher than non-fulltimers.
We sold our house but hadn't yet gone to closing when we purchased. We were also in the process of changing domicile. The dealer we worked with used our 'home' address for the loan; this got us quicker approval and 2% off the interest rate.
Advise above is right on - you should have the rv at least a month before leaving your house if only because any repairs will be much harder to do if you are living in it.