RCbob. You've started me thinking about building a Super Cub. Never have so far. The fuel caps were about 2" across and were not recessed. They went on with a half twist. They were about 2' from the wing root atop a metal cover which was over the tanks, one on each wing.
The tail braces were a streamlined wire with flattened ends that were bolted to the spars of the tailfeathers. The elevator did go to the end of the horizontal. If you are into scale make them correctly. The fuel guages were a glass tube inside the cockpit on the exposed root rib.
By the way you don't have to make it yellow. Most Super Cubs were cream with a red stripe and flash on the vertical stabilizer.