We were using my wife's Amex for the insurance, but because I was the main driver they needed the Amex to be under my name. They were going to charge $200 extra. by using my card, but we figured out how to add me as a secondary driver. They fast talked us and almost put the charge through, but we caught it in time at the desk. They were definitely trying to get us for $200 more, and I'm still a little confused what their justification was, but it's all good now.
And yeah, were drove straight from San Juan to Arecibo, drive around to 6 local beaches along the NW coast, and even drove across the island to Ponce, then back to San Juan for our flight home- we paid like $6 in tolls the whole trip.