I think that I have finally found a CO2 inflator that will work for 50+ fingers without spraying CO2 all over the landscape and not filling a tire.
Take a look at the Planet Bike "Red Zeppelin" inflator. It screws onto your tube stem. The cartridge screws into the inflator. There is an on/off regulator knob. There is an insulator sleeve to keep your fingers from freezing. It's small and cheap (especially on Ebay) and it might actually work, unlike some of the inflators that I have seen.