I don't have a pump island and won't unless I abandon my farm display and sell my windmill.But,if I do build one I'll build the whole thing out of wood.Fast,easy and in my case I can move it around when I want to change display layouts.
I think your idea of using wood light poles is a good one.Aside from cost,working with wood offers several advantages including ease ot adding on and ease of mounting other island features like price signs and towel boxes.
As for air and water hoses,many times they were just coiled up and hung on hooks.Easy to do if those poles are wood.You might also consider other common island pieces like wringer barrels,towel boxes and trash barrels.
Just things to think about.Best of luck.
