FWIW: For a rear only system, depending on how much you want to spend, your vehicle type and weight on the rear axle, I would consider either (a) just having a custom leaf spring designed for your vehicle or (b) looking into a Firestone Ride-rite or equivalent. [Or doing both.] A well-designed custom leaf (and/or coil) will be inexpensive, zero maintenance and super reliable. I have to say that the more time I spend traveling, the more I prioritize eliminating possible points of failure and reducing the amount of extra maintenance items overall e.g. I wouldn't mind having a less powerful/more reliable diesel, manual roll-up windows and a manual 4x4 shift lever on the floor, etc. versus all the power and technology-powered convenience. This applies to everything for me: engine, suspension, camper+truck systems, etc. [As an aside, I would never fault someone for rolling in a wickedly cool and luxurious new $500k-1m+ Earthroamer or GXV, but I cringe when I think about keeping all those systems operational...though maybe my problem is that I am a DIY-er, something tied to the reality where one can't find a hired team of mechanics and sources of supply near at hand when wandering the hinterland and the last thing needed is something essential breaking down.] The full Kelderman suspension can overcome many folks' aversion to complexity by adding (along with the expense and maintenance) valid capabilities like vehicle height adjustment, self-leveling and a plush ride. The 2-Stage system seems to be designed mainly to compensate for an inadequate or worn out rear leaf spring and improve ride quality. A new custom leaf (and/or coil) spring will be more reliable, far easier to maintain and come close in on+offroad ride quality (all other things being equal, shocks, wheel/tire, etc.) at a fraction of the cost...but of course it won't self-level and you will need to work a bit to get level at the campsite. For simplistic load support, minimal expense and maintenance, the FIrestone ride rite might give you what you need and also add flexibility if your rig is not a dedicated camper and you want to use it for other things (e.g. if you have a truck camper). If you do go with the 2-Stage, I would take a detailed look into what happens in the event of an airbag or other system failure: does the leaf still function or do you have to stop and swap the airbag? What extra equipment do you need to carry to do a repair/replace?, how much room will that take up, etc. I'll reiterate that I think the Kelderman is a proven system but I would examine the desired capability versus the higher cost and extra maintenance. I would also weigh your loaded front and rear axle loads and compare those amounts to what your vehicle was originally designed for, consider your load distribution and also whether the front suspension is adequate and how it will interact with the Kelderman 2-stage as well as your wheel, tire and shocks choice.