We are using
these. They're very cheap, work in the same manner as a bumper switch, and are lightweight. There will be 2 in series: The pole-bump switch will be "off" and the goal-bump switch will be "on". When we DEPLOY, the pole-bump switch will turn "on", completing the circuit and turning on our motors. When we get to the top, the goal-bump switch will turn "off", breaking the circuit and turning off the motors.
I'm sure we could do some fancy lever arm that can do both the pole-bump and goal-bump actions, yet simply adding another switch is simpler and about the same weight.