I think what I would do is change the home() routine to not go so far below the bed while searching for the home position. But the switch should get pressed even if there is plastic on the nozzle. The plastic on the nozzle issue would only cause trouble during the auto bed level probing. In that case, you really do need a clean nozzle since you are probing the bed and looking for electrical conductivity.

Still, with a reliable home (because a switch is being pressed), it would seem you can wipe the nozzle sufficiently well to be sure you will get the electrical conductivity that you need.