I think you would have a hard time finding something that would work with the weight of the motorhome along with the specific setup for a P30. Don't these systems require a lot of fabrication to replace the stock suspension? Not sure on the tank. I think a system that large would still require an accumulation tank based on the sheer volume of air required by the system.
I think simply repairing your factory system back to spec would be a cheaper choice.
Having said that - it would be cool to see how a project like that turned out in the end. Trying to imagine seeing a slammed 270 in the campground.
1986 Airstream 345 Classic Motorhome