A plug kit and a plug in the cigarette lighter compressor has saved me many an hour of aggravation. Yes you plug it from the outside.

Is it the latest and greatest way of doing it? Nope, but that way entails a trip to the tire store because you need to dismount the tire. Unless you want to rassle the tire off the rim with a couple of tire irons, BTDT, not fun. Make sure you mark the location of the weights so you can reinstall the tire properly.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.