If you are taking short, 3 or 4 day, trips I would favor using a smaller vehicle to get around. Sounds like your assignments will keep in one location for an extended period of time. You can pick-up and move a MH easier than a FW, however I would find it getting old to move on a short stay basis for extended periods of time.
Keep in mind if you are planning on staying in state/federal campgrounds the 42' rig is too long.
Fred and Bonnie
2005 Dolphin LX 6375
Abby, Ruffles & Scarlett, "The Cats"