PVC is not a good thing......gasoline will break it down over time.
You might want to take a look at electrical conduit. There are threaded hubs or flanges that bolt onto a service panel, and they are sized in 1-1/2" pipe thread (plus other sizes). A bonus is that they're aluminum. If you combine that with an "IMC" conduit nipple and cap, that might do what you want with little weight penalty. I can not say how it might be to weld it, though.
Just brainstorming.....Roger