A 5th wheels rig costs significantly less than an equally appointed gasser motorhome, and even less than a DP.
The "month test" mentioned above is the usually the decision maker I have heard of on occasion, if you can get by with the big tow vehicle as your daily transportation, (and don't want to purchase a second commuter vehicle).
I have run into many, many fulltimers living and working fulltime near major metro areas. The price of fuel spent commuting 20 to 30 minutes in each direction to the job site, (or work), in a big pickup truck 5th wheel tow vehicle is prohibitive.
So, the motorhome and toad combination return into the discussion, (even if staying in one place longer than a month), if a cost-effective high gas mileage toad makes better sense.