Corrales, I can't advise you about recent Aduana requirements about titles. We drive only a car in the hassle free zone and don't import a vehicle. I have heard that if you drive a motorhome only, you don't need to import it in the hassle free zone. You may get by with only registrations, if your registrations do not show a lien on your vehicles. We have never needed original titles, only photocopies.
Another resource is vivasancarlos.com. There is a free forum on the web site but you must register to use it.
Ask on that forum about titles, motorhome only, ect. Also I am sure you can meet up with somone coming South if you post on the forum.
The RV Park in San Carlos is Totanaka. It is on the main drag on the right as you enter town.
Come on down, I am sure you will enjoy your stay.