oneaddicted: I would tend to agree with what others have said. Given your line of work, a diesel probably makes most sense for you in the long term.

But, if I may ask...
1) Where are you located? Are you usually/typically pulling over mountains?
2) What is the typical size of the RV you transport? Are most the big, 35'+ 5ers?
3) What are the typical differences in gas vs. diesel prices where you reside?
4) I would imagine at 330k miles, your 6.0 is getting somewhat tired. Have you considered swapping in a newer 6.0 power plant? Or is the rest of the truck just as tired?

By the way, I went from a diesel to gasser myself in the past few months (to a V10). But I don't tow nearly as often as you.