Re:8 inch pvc bumper mounted water tanks?
4 years ago there was one state inspector that covered trucks,now the are 5 covering our county alone,the older trucks are grandfathered somewhat,but a new build would no longer be able to use that system.
The plus side? A 30 gal fresh with a 45 gal waste carriage mounted tanks is $212 delivered ,PVC probably $50 at most.
Mounted on roof heats water and has gravity flow,not sure if it heats up to the required 130 degree but worked back in the day when nobody really paid attention.