NellyBelle.....I'm 6'2" 330 and have never tried the bench. I think that would be pushing it to it's limit. With that said, if you really feel safer sitting on it, have a stainless arm cut to fit and attach it to the underside of the front edge with a pin that allows it to swivel with the seat up or down. When up, the arm would lay flat against the seat. When down, it would give plenty of support to the front edge.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor