We've been on the road for two years and have worked from Georgia to Guatemala and most everywhere in between. We wrote a blog post not too long ago about our approach that you might find helpful.
How to Build a Mobile Business
The first thing I'd ask myself is this "Why a Class A?"
You already have a 5er, which means you already have a tow vehicle. It seems to me that your cheapest option will be to trade in your old 5-er for a slightly bigger one.
One big advantage that 5th wheels have over motor homes for full-timing is that when you have engine or transmission trouble, you don't have to bring your house into the shop.
I full-time in a Class A, so my comments don't reflect a personal bias toward our own setup. It's just an observation from a fellow fulltimer.