Mark; No doubt, those would provide a much more secure fastener than simply screwing into glass. Funny you should mention that. When I had my tank out for the 60 horse motor installation, I stared at those tie downs; thinking about what might be a better alternative. Although I never did it, what crossed my mind at the time was replacing those screws with nylon toggle anchors.......you know, the kind you hang things on sheetrock walls with. My thinking was, not only would they be much more secure, but would be impervious to salt as well.
Yat