No can do. I have zero cash and these were given to me. So, I'm working with what I've got.
Maybe I'll put it near the stock antenna, but on the driver's side.
My whip and spring were under $20. But if I had to use a fiberglass, I'd put it in the middle of the bed, right behind the cab. I figure that would provide the most protection against tree branches. Of course, that is what I did with my second one and it still died on its first wheeling trip. Maybe you could just buy a spring for it?