Got a picture of your current setup?
Might be worth it to replace the entire console with one that includes the seat built in. Or have a miserable experience working with fiberglass. Okay maybe I just don't like working with fiberglass, and my tools have excellent dust collection.
This is similar to what I have in my little boat. I did widen the seat base so my wife and I can sit together on the front seat. Also widened the rear seat to fit three smaller butts across.