Here's a cool brass insert to repair bad screw or insert pull-outs: https://www.boltdepot.com/Product-De...?product=23872
Drill damaged hole to 3/8", screw and epoxy in this beast, and use a syringe to put down a layer of epoxy at the bottom of the hole to seal out water. After the epoxy sets, grind it down flush with the topsheet (use lots of water while grinding to keep the insert cool, so you don't bake the epoxy), and use the same M5 machine screw that you use for regular inserts.