Originally Posted by
Creakyknees
ehhh... why don't you just get seatbags for the other bikes, and use the opportunity to teach them how to change their own flats?
That's Rule No. 1 for family cycling: Everybody fixes their own flats. I often wind up doing it because it takes me a lot less time (years of practice makes semi-perfect), but everybody knows how. Every rider also carries basic tools and a pump, though when we all go together, we might leave a pump or two behind.
I don't know those specfic rims, but I'd be leery of drilling the holes out unless they're pretty stout. Any bike shop can sell you a presta-to-Schraeder adapter for a buck or so, and you can store it screwed right onto the valve, like a cap. All my tubes and pumps are presta (13 bikes in the family), but I carry an adapter anyway, just in case everything breaks at once and the only air source we have is a gas station hose. And there are lots of pumps out there that will handle both types, either with or without a minor adjustment.
Schraeder valves really aren't ideal for bikes because you have to overcome the spring pressure when you're inflating. With a standard frame-fit or mini pump, that can be significant...to be honest, I never have thought of valve compatibility as a problem. You can't carry the pump you use for the boat trailer or ATV or whatever on the bike anyway, and I never ride without a pump, so I just carry one that works.