Blazer tank installed in swb step 72 filler help needed

[WIDESIDE72]

I installed a blazer tank on my 72 swb step and am to the point of installing the bed wood. Does anyone have any pointers on installing the filler? I wanted to do a side marker fill but the body shop wasnt interested. I am going to drill a hole in one of the boards and install it in the bed. I bought a flush fill cap and some 1-1/2" fuel filler hose. I also bought a 1-1/2" 45* but it looks like that wont work.