Yikes that’s a lot of force on 4 screws. Can you through bolt it to a backer plate, with fender and lock washers? Even a snap toggle would give more strength than a plain 1” screw.
Backer plate would be my first choice by far with stainless.
This if couldn’t get to it and I’d probably paint it with a couple coats of paint too. You could replace the bolt to stainless easily. The backer bar not so much.
https://www.homedepot.com/p/Hillman-...448112#overlay