Vapor Lock problem

We are having trouble with a fuel cell vapor locking. It was made so that it houses the stock sending unit. It does not have a filler neck on it. The cap is flush with the top of the fuel cell. Any suggestions on how to stop the vapor lock.

If it is on a fuel injected engine it needs some sort of vent

How would you suggest venting it so that water cannot get in? It is an open bed truck that is driven daily.

put an NPT port on the top of the cell, then run a line off the top over and down. This will stop any rain from getting in.

put the stock vent in the tank that is supposed to go to the charcoal canister...

Im not running a tube up and out of my tank...that will look absolutely stupid. This is my truck by the way my buddy just posted my question for me at his house. It is an open bed with everything exposed. Like so..