BigJohn's suggestion is probably what I would do. If you simply use bigger screws to replace the stripped out holes, those are likely to strip out/not hold, either. There is a product called MarineTex, used for patching small holes in fiberglass boats. It is a white, two-part epoxy that can be sanded and shaped when dry. You would then simply re-drill pilot holes for the existing screws. That might be an option, but I'd be concerned about it looking "patched". The suggestion above is permanent, structurally sound, and done right, would look good.
2016 Jay Flight 33RBTS
2008 Ford F350 Super Duty 6.4l