So... I just tried this and I thought I'd let you know how it went.
I used a bit gag and ran bungee cords through the rings on each side of the gag. I hooked clover clamps on one end of each cord and weights (probably was about 8oz, actually) on the other. I skipped the enema entirely (not quite my thing, even the non-carbonated kind), but I added a ball parachute with about 1kg attached to another bungee cord. I wrapped my calves and feet in cling wrap, with a little duct tape on the feet to make sure the cling wrap wouldn't come off accidentally. I cuffed my hands behind my back and locked the chain to a hip harness to ensure that I couldn't reach the gag, clamps, or parachute.
The setup worked perfectly: I couldn't move forward at all without hopping, and hopping caused significant bouncing of the weights attached to my balls and nipples. I had to pause a couple of times to stop myself from cumming. It was actually a pretty challenging scene -- by the time I got to the keys I was covered in drool and sweat. And then I realized I hadn't left anything to cut the cling wrap with, but once I unwrapped a few layers my feet slipped out pretty easily because of all the sweat. :-/
Great fun, thanks for the idea! Although it is quite dangerous (I did almost fall a couple of times), and I agree that it's probably better left unattempted.