I can't help you with a waterproof case for your 722 (I'm still looking for a submersible/waterproof case for my 715), but I do know of something that has helped me tremendously with keeping my infusion set from pulling out in the summer heat.
I bowl in a summer league, and where I bowl they have NO air conditioning. The first year I bowled there, I had to bring an extra infusion set because mine would ALWAYS fall out during the first game.
I got turned on to Tegaderm Patches and have not had one infusion set fall off in 2 years. The link is for the right size to cover my Paradigm 715 Sof-Set Ultimate QR (MMT-317), but you might want to go bigger depending on the area your 722 infusion set covers. I use 2 patches with each infusion set change: one patch horizontally and the second patch vertically.
Please be aware that the link is only for information purposes. Most health insurers will cover these as long as your doc gives you a script... and you should be able to get them at any durable medical goods store.
Good luck Cody, and if you do try the Tegaderm Patches let me know how they work for you... and when you do find a good waterproof case, please let me know too.