I'd take the truck and fifth wheel. I wouldn't feel too good about letting my kids or wife roam around a MH while underway and even strapped to a couch I don't think it's as safe as being in a crash-tested truck with airbags all around. Plus when you park the trailer you have the truck as a handy vehicle to get around in, and when you have the FW parked at home the truck can be used to commute, haul around stuff, pull a utility trailer, etc. I also think a truck and fifth wheel is pretty hard to beat as a stable and comfortable combination to pull down the road. I admit that I've never driven a diesel Class A so maybe they drive easier - I'd have to defer to others on that comparison.
