What limit switches would be necessary for use in series with a DeWalt 20V cordless drill battery?
Limit switches don't have to carry all the current, but they can drive a relay that can!  I'd go for a normally open relay, with limit switches designed to close the relay when all is good -- this gives a better failure mode (motor off!) if things malfunction. It's probably not as ideal as a direct cut of current to the motor through your switch, but it should get the job done safely.

Think hard about all your failure modes as you go through this exercise!