Our Prevost came with the levlow system. When we park, I use the control valves to level up the bus and then place wood blocks under the rear engine cradle and frame (4 points) because the rear will leak down in a few days while the front stays up and level for eternity. This keeps us level and solid when parked for longer than a few days (usually by the month or longer) and the bags aren't crushed from being deflated. We also have a portable compressor built into the area behind the front bumper that I can turn on to pre-air everything before firing up the diesel so we can get moving faster. I originally installed it to keep the bus leveled while parked, but I couldn't adjust to the sound of it coming on in the middle of the night. It usually only comes on once a day when parked like that though.