Is there any way to PERMAMENTLY eliminate rear main oil leaks?

I've used the "Real Gaskets" first hand, so I have DIRECT experience. I was optimistic, given all their marketing talk. Plus, they are very cost effective, so it didn't seem like they were after my money
Disagree on that last point there. You mean "affordable" or "inexpensive". "Cost-effective" doesn't mean the same thing; it means a thing that works well to meet whatever need, at a reasonable cost (lower than other ways of meeting that same need). A thing that doesn't meet the need, or works poorly, cannot be cost-effective even if it costs $0.00.