Yo, TangoFox,

Must be the water in NJ...

Recently Busted,

I would keep fluid in the system to prevent oxidization of cast components. Moisture can seep in and cause damage without the fluid - and fluid is alot cheaper than Master Cylinders and Calipers.

Tango's idea of preventing air from entering the system by capping the reservoir sounds interesting. You might also make sure air doesn't enter in other places by either capping, plugging or immersing in brake fluid container.

The Mityvac comes with a bag of rubber plugs and things. I will bet that one of those plugs would fit in the brake line.