I ended up installing tie downs in the four corners inline with the stake pockets using a threaded nut plate in each stake pocket.
The plates were a bit of a challenge to get in place inside the stake pockets but I was able to use a grabber tool to grasp the plates and lower them into the correct area (working past the stake stops) and then initially using a long bolt to capture of the threaded holes. I used the long bolt to move the plate into place to start one of the correct bolts into the other hole, remove the long bolt, and install the second correct bolt.
I am sure that the tie downs are overkill but they fit the robust nature of the 3600.
