Jeeps/4 X 4 are always at a premium.
We will be on the island the 17th - 29th at the Tamarijn and it is sold out for most nights. The island will not be deserted.
In the past, even during low season we have had to call around to find a vehicle at the last moment, a day or two before we want it.
I have tried to get a jeep without making reservations in advance and it is nearly impossible....I now make reservations as soon as I know I am going to Aruba...which sometimes means months in advance....
Try Aruba Royal, Amigo or American...those are the ones I use most often, but I imagine any othe them are satisfactory...well except Avis of course...we don't rent from them,,,,do we???!!!