I have just finished fitting mine today. My tow bar bottoms out on the road when getting off the drive. Fitting semi air and inflating to 3 bar has raised the rear by 80mm which I hope will be sufficient. I shall give it a try next week.
I have two independent lines and 2 gauges with valves. No compressor but use a small handheld rechargeable pump. It looks a bit like an electric drill. I alter them for a bit of levelling. I can do it with a small hand bike pump but when I get above 4 bar it gets difficult.