I didn't do a taillight gas filler install but I did do a stake pocket filler install. Yes it is a pain to get things cut out inside the stake pocket. I can't exactly remember what we did, this has been a multi-decade restoration, but it was probably a combination of hole saw and sawzall with a long blade. I also ran into the problem with fuel fill hose and decided to go with a
mandrel bent stainless tube that I bought off the jungle website. I connected the filler cap to the the tube with a piece of fuel fill hose and had to get a neighbor to help me get everything in place because it had to be installed from the bottom. Wasn't fun. My tank is under the bed and there is only a slight drop from the stainless tube to the tank. Still trying to figure out how to do venting, hopefully the vent ports in the tank along with rubber tubing will be enough to keep me from having to take a half hour to fill.
