I've seen video of LE searching a phosphate mine (which to me, looks like a hole that's been dug straight down), but was there ever a statement to the effect that an exhaustive search of all of these known holes was ever made? Seems to me that this might be the most logical type of place GG might have dumped RG into. I know that this goes against the insurance claim motive, but perhaps this was his "retirement plan", to collect after 7 years. If, perhaps, he killed her by strangulation, which seems to be his typical modus operandi (or at least his most common tactic with women), then perhaps he couldn't risk having her body found in the water, because how else could that have been explained to LE.
I still believe that all of this snorkeling nonsense has just been a big diversionary tactic cooked up by GG. What's really convinced me was that even his first attorney stated in a video (in a link that was provided by Dushi quite a ways back) that they were "sunbathing", to support the placement of the towels on that rocky surface. Since more than one witness has said they left the area, he had to have placed those towels there upon his return. And perhaps RG did cut her foot strolling that "beach" area and used a towel to apply pressure to the wound. He had to have planted that and her dress there as well.
Lastly, and I apologize for not providing a link, but I have seen some panoramic views from other locations on the island. I believe that the one in question was from the vantage point of the highest location (perhaps also near where the cliffs are located?) in Aruba. In that view, I noticed what looked like many wooden platforms scattered all over the ground. To those of you who are familiar with the island, were these used to cover the phosphate mines that were once there? Maybe all GG had to do was lift one of these "covers" up and dump RG into the hole? It wouldn't surprise me if these holes were also filled with water at the bottom, maybe even enough to conceal a body when simply viewed from above.