You can use any seat, assuming you want buckets? but you have to build a short platform to bolt the seat to, which will allow it to go over the raised lip. Now u can hinge it like the bench. Do the seats first then build your step. I think I would build up the platform using fiberglass sheets with aluminum plate sandwiched in for support and front and rear lip, so you can bolt thru or rivet the hinge. Hopefully you have the same image in your head that I have. Hope this helps!Pete