Well, for best results, they will need to be trough bolted to the floor or deck, you will need to be able to access the back side of the deck or floor. If you can't access the back side there are fasteners that will allow you to only access one side, there is a SS molly bolt nut that is used for blind installations. I got some at my marine supply place when I installed a console a long time ago, don't know the name but will look to see if I can find them. Of course there are also huge pop rivets that could be used, not sure how big they make them but I am thinking along the lines of 1/4".
The ones I used were similar to a hollow wall anchor (molly bolt) but were stainless steel.