After being in the biz for almost 40 years, including decades of fiberglass repair, prototyping, and production.

I always think of fiberglass-to-metal bonding as temporary. Eventually it will delaminate from the metal somewhere. One problem is the expansion rates. As glass heats up and cools down, it moves farther than steel... so every day it's a "push-pull battle" as things heat up and cool down. I would advise steel.

Since we are on the net... someone will disagree... but it's your choice.