Hymer Bottoming Out - Air Suspension Help Please

Hymer Bottoming Out - Air Suspension

Hi Everyone,

Can anyone please help?

I have a Hymer MLi580 which is on a Mercedes Sprinter 316 CDi (Year 2014). 

The big issue I have is, on a few occasions when there is a relatively steep incline, the rear end of the motorhome bottoms out on the road. I have also moved home recently and even the drive immediately from the roadside to the start of our driveway is much steeper than originally anticipated, so this does the same and bottoms out. The big issues is the fact that the body of the motorhome overhangs the rear axil by 2.2 Metres and with nearly 2.4 tons on the rear axil doesn't help. 

It appears that what I really need is to have air bags fitted to the rear axil to lift the axil and hence the back end of the motorhome sufficiently to avoid this. I have looked at some options, to which most suppliers and fitters recommend the dunlop air bag and compressor system. The only problem here is, I cannot get any certainty from anyone as to how much this will lift the rear end, which needs to be by at least 6 inches. I have an old friend that has suggested that I need possibly HGV heavy duty air bags that could lift up to 10 inches. Again I have contacted several companies, but no one can give me any certainty or guaranties that this will work.  

Can anyone help, perhaps even someone that has already fitted an air bag system to a Hymer and can say from experience exactly how far this lifts the back end? 

Please I realise there may be 1 or 2 obvious comments made such as why don't you change the motorhome to another model and blah blah. Reason we love the motorhome we have and does everything we need it to do and really don't want to change it. So please refrain from these jokes. Any genuine help and advise would be really appreciated.