The truck.....assuming that 3500 is a diesel is it also 4x4 or limited slip?
The 5th wheel....you might consider signing up for RV Consumer. It's much like the Consumer Reports for the RV industry where they rate every RV by model and year (you can narrow your search just to 5th wheels and even my year, etc.). They rate on reliability, value and an overall star rating. They also rate each unit by weekender, vacationer (up to two weeks), snow birder (up to six months) and full timer (year around). What they don't explain is if you can live in a unit for six months comfortably, why you can't live in it year around comfortably if it's a true "all seasons" (thermal pane windows, heated holding tanks, plumbing up in heated space, enclosed bottom, etc.).
I was looking at a particular make and model of 5th wheel (hey, it looked really nice) and somebody made the suggestion to me about RV Consumer. I'm glad I took the suggestion.......I was about to go straight to the bottom when I jumped off that cliff. As it is, I ended up with a 5th wheel that has very high ratings, didn't bust the bank, is a true "all seasons" trailer.
Another tip.....if you're wanting to go "new". Once you identify the brand and model that you've settled on, do a search for a prior year (2011 or 2012) that's still sitting at a dealership. If it hasn't been sold or registered, you'll get a huge savings below the current year's model. And about the only thing that's different is the interior colors and the exterior graphics. I learned this one to late but I did get my 2013 just a couple weeks after they came out at $5k below MSRP......$10k below would have been much nicer.