This is a far more complex question than you will ever get all the answers to in one thread. Gassers ride much worse than DP due to the lack of air suspension. Most of the fixes available are listed in the previous posts and you just need to spend some time researching things and making some decisions about if/what you want to try.
I'm not an owner of a class A but have done a ton of research in preparation for one. Of course, a DP would be great but I'll likely start out with gas. I'm mostly interested in safety upgrades to make the coach handle well in all conditions and to that end the Sumo springs look like a great option.