As noted, someone will attempt to plug something into it they shouldn't. As well, SOME fans (we have one) draw some significant power. Therefore,
1) Use 10 gauge wire. It's 10 feet each way, and that's what counts (20 feet total).
2) Use tinned wire. Seriously, when you sell the boat, someone WILL notice if you uses untinned solid wire.
3) Run it through the panel, where it belongs. It's the right thing to do. AND, in the event of a fire, your insurance
company won't be calling you names and/or denying your claim.
4) I know all of this, because this is EXACTLY the same project
we are working on. I thought 14ga, a buddy in the business told me NO. Use 10ga. You never know what someone might do...