taking your own boards is a must- there are hundreds of little-known breaks where the nearest shop is an hour or four away.
Keep an eye on keeping your wax from melting. I keep mine in the cooler most of the time.
A twin-fin fish is a great all-purpose board, you might also want something like a gun, there are some big waves during the dry season (starting soon!!). That 10-0 is a great "ride any day" board, but keep in mind that with howling offshores it is nice to have at least one board that'll let you drop in.
At the least: get a decent board bag to protect the boards and keep them out of sight.
I've seen a few board-lock systems for sale, most use either the leash plug or somehow attach to the finbox. I've never used one, but would seriously consider it for the peace of mind it'll offer.
Surfboards are high-value and easy to resell for thieves. Which stinks. But better to be a mote paranoid instead of bummed out after the fact.
The tent looks like it'll work well for you!
Finally: I can't speak to Guate, but finding 16" rims, used, in decent shape down in Costa Rica isn't easy at all. I don't know where all the used rims go.... but they appear to stay there.
There are a few guys on the board from Mex, Guate, and El Salvador. Maybe they can help point you in the right direction should you decide to buy stuff down here.
Thanks! For now I am putting 2 longboards, a 6'6" fish, and 1 more fun board on top. I have four boards going, inside won't work, 1 is 10' long itself. I had thought of buying/renting boards along the way, but would rather deal with taking them, and being free to surf all the time, my boards.