Adding a fuel tank vent - where to run?

I have a new aluminum fuel tank with a provision for a vent. The OE tank it replaced did have a vent at some point but it was capped off and there were no lines coming off the tank. There is no existing charcoal canister. Not sure if I have a vented cap or not but I would say no. The cap is plain on the outside, painted body color.

So I would like to add a vent line. How/where should it be run? Not too keen on just venting to atmosphere...

Thanks for any input.