I have never seen pressure regulators used for ride height, frankly I am racking my brain for why it wont work and coming up blank.
on the one hand if you have a leak the system will just leak down to the ground then lift back up (slowly) when you turn the compressor on. on the other if you have a leak free system the compressor will never run at all.
I would want to drive it and see what happens, as a wheel goes over a bump the bag will displace and with regular valves the pressure will spike, but with a regulator I am not sure of the mechanism, it may be like an adjustable check valve?
speaking of check valves, you might consider them because a hole in a line or a bag would drain the whole system and leave the whole truck flat.