For road touring I think they'll work fine for shorter tours; for longer trips get another pair and mount them low rider style. That would be enough space for a one or two week long trip, I'd say.

Bungees and hooks were the standard back in the day... if any of the parts failed, repairs could be made with parts commonly found in a hardware or auto parts store. That's a big consideration if you break down in a small town with few facilities, much less a full service bike shop.