Any thoughts on using hi-temp RTV instead of gasket on engine side cover?

I don't see why it wouldn't work. I've never had it apart, so maybe someone who has can shed better light. The only thing I can think of that might be a problem is the thickness of the silicone when it's compressed and bolted together. The fit may rely on the thickness of a paper gasket, and silicone will be thinner, so there may be some interference issue. I doubt it though, it should be fine.