The only SM PADI Cert would be a distinctive specialty until after DEMA. There will be an "official" rec and a tec course available at that time from what I've been told. I'm not sure of any other training orgs offering SM Cert cards (I'd be surprised if there wasn't.) I understand why a dive op would request proficiency in an unfamiliar rig to them (safety) but demanding a cert card that is only distinctive at this time seems silly. SM makes a lot of sense for a lot of reasons outside the caves. I too would like to read the OP's post trip comments.
IANTD has been offering a sidemount class for a few years. In fact, they were the first agency to offer a basic sidemount course. They also offer an Advanced Cave sidemount course. TDI just unveiled a sidemount course a couple of months ago.