There is no doubt that the Right Stuff RTV will seal the oil pan to the engine without a gasket,but i hope you never have to remove it for any reason. I used the Ultra Black RTV to seal my transmission pan to the transmission without a gasket, then a year later when i went to remove the pan to change the filter i had to destroy the pan getting it off. I also used the Ultra Black RTV at the same time to install my valve cover on my 2.3 inline 4 cyl and a few months later i tried to remove it by prying on it and using a rubber mallet and it wouldn't budge one bit i gave up trying to get it off,so the valve cover is still on there but the good news is it doesn't leak,haha.
I would just get a good cork gasket for the oil pan and if needed use the regular strength RTV.