we could have a case where crashing surf rendered the airframe into scrap with a fairly good sized chunk somehow anchored in a groove on the reef, maybe near the drop off.
As you've noted, what we think we know about that location suggests that there wasn't enough water there to hide a good sized chunk of the airframe beneath the Bevington Object - but we must always recognize the possibility that we could be wrong.
In Idaho I was impressed by how HEAVY those landing gear components are. From Lockheed documents we've now calculated the weight of the stuff we think we see in Bevington Object and it tips the scales at something over 250 lbs. I'm re-thinking the need for this piece of wreckage to be hung up in a groove. In the absence of a major weather event (unlikely at Niku between July and October) I can easily see a 250 lb. object remaining in place on the reef for three months. The simpler the sequence of events required, the stronger the hypothesis.
1. Airplane lands on reef and sends distress calls for the next three, possibly as many as six, nights.
2. Rising tides and surf move the plane enough to cause the gear to fail much as it did in the Luke Field accident.
3. As the plane is pushed along the reef surface on its belly by wave action, one of the main gear assemblies separates from the airframe just as it did at Luke Field.
4. The plane goes over the reef edge, is beaten apart in the surf, and sinks out of sight.
5. The wreckage of the separated landing gear remains on the reef at least until October when it is inadvertently photographed by Bevington.