I don't know how much you could sell your generator for, but it would seem to me you would be better off selling it and getting one without brushes. I know that I wouldn't want to have to be working on a generator when on the road. YMMV The cost of working on generator plus the slide tray would offset some of the cost of switching generators.
So far, I have never had to work on the generator on the road. I would like to be prepared to do so if necessary. I'm hoping that if I replace the brush assembly and blow the dirt out daily in the desert that I won't have further issues. I made it from 2006 until 2011 with no issues. I blew out 1/2 inch or more of dirt last year.
I did talk to Wrico today to see if they make a slide that might work and the gentleman I talked to was recommending a brushless generator head. Generators have gone way up in price since I bought mine so a swap for another generator isn't in the budget.