Using an anchor bridal attached to the two side d rings is the best way to go when anchoring your SIB. The boat will ride better, not kite around as much and you won't have chafing issues on the tube tops. I do take a slack piece of the anchor line and tie it off inside the boat as insurance. Attaching anything heavy or with leverage to the aluminum flooring is always a challenge. The top sheet isn't strong enough on it's own, it will flex and crack under load if the attachment point is small in surface area. However, a nice aluminum plate across the aluminum floor that bolts to backing plates inside the hollow floor sections, which key into the locking side rails is very effective.
Rail sections are great for strapping things down, but any twist, rack or play in a heavier or more leveraged assembly will lead to wear. My Zodiac Futura track didn't like the play in my seat assembly and this is the result.
None of the equipment, console, benches or ski poles that are attached with backing plates and cross plates has had any issue at all. Just a suggestion for a possible method of attachment to your floor.
