The Ford Barn - '35 Ford Coupe Rear Fenders

Got my dads '35 ford in the garage and due to Mr Ethanol, I have had to replace fuel tank, pump, filters, and rework some rotten lines. This is an all steel, original shaped (no chop), street rod which is running a '93 5.0 EFI engine. I have put the high pressure EFI pump in the tank now and I need to install a tank vent tube which needs to be higher than the tank filler neck. This is impossible to do with a '35 without venting into the rumble seat area and so I am forced to install the tube as high as possible in the fender well. There are 6 or 8 bolts which attach the rear fender to the body that I can see inside the wheel well. Are these bolts screwed into capture nuts or will I need to remove part of the interior to expose a nut? I need to use one to mount the vent tube and roll over valve.
Thanks in advance....