Use PostgreSQL hstore to store the many varying fields of any given AOI feature into a single column, say attr, starting with load_sanctuaries.Rmd.
See:
CREATE TABLE books (
id serial primary key,
title VARCHAR (255),
attr hstore);
INSERT INTO books (title, attr)
VALUES
('PostgreSQL Tutorial',
'"paperback" => "243",
"publisher" => "postgresqltutorial.com",
"language" => "English",
"ISBN-13" => "978-1449370000",
"weight" => "11.2 ounces"');