Any moisture would be as a vapor in a vacuum, even though it wouldn't go anywhere. Then in theory I could turn the vacuum pump back on and it would suck out the water vapor. I was thinking it takes time for the water to boil off to a vapor and as long as the vacuum stays low enough it should all be a vapor.

That was my theory, not that I checked it, I still ran the vacuum pump for a while. My real intent was to check for leaks and I don't have anything good to pressurize it with.