You could try to use male/female connectors. Make the hole the size of the connector, glue it in place. That would reduce resistance. You could wire direct, and glue around the wire, but you wouldn't be able to disconnect it.
I've been thinking about this with metal lids. Make the hole a little bigger, put in a non-conducting insert, extend it a little bit on top and bottom so you are sure not to have bolt/metal contact. Just a thought.
Hook a a volt/ohms meter and see what is going on.