I just pulled that bench apart as the plywood was dead. Replaced it with Starlite (www.boatoutfitters.com
, then a bit of cutting and drilling at home). I went the same route as you Bella Serra, but used 2 long bars of Starboard screwed to the underside. Helped A LOT!
And I think (we'll know over Thanksgiving when I install them) to those clips (I agree, pieces of crap that break! I bought like 5 last time a few years ago. 1 left!). These look like they will work:
You can find them here
or even cheaper most anywhere on the internet.
The 3/8 diameter is just right for that loop, they flex a bit so you can open them to receive or remove that loop but seems tiff enough to do the job, and I fgiure two in place of each bracket should be strong enough (time will tell)!