It should be driven, extended operation at idle is not recommended. Much better to occasionally get on the road for 20 miles or more to warm everything up and clear carbon and circulate the fuel.
Prior RV was 36' Dp with Cummins ISB. Annual maintenance was about $200 DIY oil and filters change, lube chassis. Every 2-3 years, Engine Air filter, and Air Brake filter added about $100 each..
Having service done by a shop reported to be about $1100+...
22.5 inch tires are in the $500-600 range each.
But: The Rear engine diesel is quieter, more stable and comfortable to drive. My ISB consistently got 11+ mpg.