I've thought about getting a Sanke keg, adding a pressure gauge port/regulator to it and fermenting in it to give this a try. I would remove the spear and then come up with a way to seal it. Might even just reinstall the shortened spear when it's ready to carbonate. That would not only seal it, but give me a way to transfer the beer when it's ready.
It's not something I have to have, but it would be fun to try.,