Kudos to Patemey for the ingenious idea for making big holes out of little holes. Kudos also to Janice 142 for suggesting that I buy a cigarette lighter adapter USB charger and forget drilling a bigger hole in my boat.
Both are great ideas but rather than spending more money than the plug cost on hole saws and mandrills, I am going to Walmart and buying the $2.97 version that also has two power outputs.