It's certainly worth a try. 220 backs are relatively cheap, because 220 film has been gone for a good while, anyone who has a stash already has cameras and roll film holders for it, and it's not likely to come back as a mass produced item (despite rumors Shanghai is planning to reintroduce it).
You need a way to lock the main section of the first roller on the supply end of the insert to the small wheel at the edge that actually drives the frame counter -- I used a wrap and a half of electrical tape, but I may try to come up with something that will stay on better (perhaps silicone tape or a careful application of silicone caulk between the two parts), or else you have to guesstimate how far to move the lever (and how much to compensate as the film builds up on the spool) and dance with the double exposure lever (since the back won't tell the camera it's okay to fire the shutter if the frame counter hasn't advanced). It's a waste-saver to cut the trimmed leader square on your film, and attach a leader long enough to replace the 120/220 start section, at least up to the film start tape (this isn't required, but a 24 exposure roll is disappointingly short otherwise -- you waste almost half of it loading and advancing through the fogged leader). You can even take up to a cassette, to allow reloading without a changing bag (I used 35mm to 120 adapters, one set on each end, for this). and make a frame mask to cover the sprockets (or just use a mask in the viewfinder to let you compose to crop them off).
IOW, you can do this as basic or as sophisticated as you want. I'm headed for "Wow, I thought you were on a budget, how can you afford an Xpan?" -- my next RB purchase will be a 65mm lens, and then I'll start hunting for a bargain on a 50mm.
