How do you guys keep gas from spilling? 66' Dart

......OH MY LANTA!!!! now it all makes sense why there was numerous rolls of TP in the trunk of my 66 when I bought it! I figured the previous owner had some severe case of IBS or something. haahahahahaa!!!! I fixed mine via using a 67 coronet center cap from a hub cap, that says "dodge division" to cover the hole, and mounting a 13 gallon fuel cell in the trunk. feasible? probably not in most cases. Do I like it? yes. its functional and simple. :) So, anyone here need a standard chrome gas gap AND a matching locking cap for an early-a? also have the filler neck + tank as well.
I put a new tank and all new lines in my 68 fastback, w/ an extra vent on the tank. It hasn`t boiled over any yet, but I take a 14" wide piece of plastic w/ a paper towel underneath it, and masking tape it tight, up under the flip top opening when I put gas in it. The plastic is long enough to almost reach the ground. I sure would get pissed off to start messing up a new paint job! Carry the plastic and masking tape in the trunk, along w/ my favorite fuel additive .