Salvor6,
Before we salvaged the 'Capitana' (1654), the law was the payoff would be 10-year Ecuadoran bonds based on the intrinsic value of our finds. The un-attractiveness of that law was obvious. As you know, we got involved in having the law changed to a 50/50 split of the silver salvaged. The new law opened the door for us and others who followed.
To answer your question, I don't know if search, salvage and division could be possible but if a permit is given it will include being tenacious,having a good marine lawyer familiar with the politics, and an excellent business plan that would include conservation, preservation and presentation of the findings to the public.
In the recent past, I know one could take a one hour tourist boat ride to the island, stay a few hours then return to the mainland. I'll say no more on that, but I will add that what Ed went through in an attempt to raise funds to return to Isla de la Plata is, to me, sufficient evidence that he may have found a silver bar. The naysayers will state Drake didn't go to that island. I say "Who cares?". If silver bars lie in the shallow waters there and are retrievable (permitted), who cares whether or not Drake left them there?
Marx's book was first to put me on to this treasure. In his book he references Nora Serling. I attempted to contact Nora (then age 95) at an East Coast nursing home but they said she would be unable to discuss her book. But her book had a bibliography and one of those references led me to Nora's source. And in that source was more information that caught my attention--to this day.
RIP Ed;and thanks for rejuvenating the spark to search.
Don....
move along move along... 
