Keep forcing the issue!
PteJack, don't stop and don't accept what you know won't work! I'm looking pretty deep into this issue myself. I'm thinking the 3500's are right on the edge of being enough to do the job for the retirement trailers I'm looking at as well. Meaning a 41'+ 5th Wheel toy hauler with 2-3 slides. So i'm looking that the RAM Chassis trucks 4500 & 5500 series. You can't get ALL the bells and whistles, but they'll pull your house off it's foundations and get you 12+MPG to boot!
Keep the faith and keep us posted!!