"DW read about the higher maint costs of diesels, so looks like we are going with gas
I think this depends somewhat on the amount of travel miles you intend to incur.
The farther you travel the more comparable the cost of maintenance. (Oil change every 5,000 miles on a gasser vs 15,000 miles on a DP. $50 x 3 equals $150 or close to a routine oil change at Speedco on the DP.)
The DP is quiet travel, good mpg for the weight carried, and likely has heavier house construction components.
If 12,000 miles is not going to be your annual travel in the rig and you will need nothing longer than 37', the gasser will probably be all you need, IMHO.