I had to lower mine to replace the starter motor. It was a similar setup to what you're describing, a cage/frame that attaches to the generator and is hung onto the RV framework. The generator is unbolted and lowered from below. The framework on mine had the bottom portion (where the generator proper mounted) attached to the verticals with eight bolts, two at each corner, which made dismantling things straightforward.
Aside from clearance under the RV, the actual lowering and raising wasn't too terribly difficult with an automotive floor jack. A transmission jack would have been even more convenient, but one uses what tools one has available. (I wasn't clever enough to check the clearance beforehand, which meant I ended up changing the starter with the generator sitting directly below its mount and the outer cover wedged up in the mounting cage...not the most convenient, but easier than raising it up again to drive the RV onto ramps!)