It may not be as big a deal as one would think. First is that the rig will pick up some fat from the meat when the hopper is loaded and that may be enough.
Failing that, the cooking oil mentioned above, is not too bad of an idea.
Grinders and stuffers can be lubricated with FDA-certified food-grade silicone spray lube, too. That is available from The Sausagemaker. I use it on my grinder and some places on my stuffer, but the stuffer seems not to need much help.