I would say that the answer depends on who you rent with. Some companies are much better than others.

Also, what day of the week? Saturdays are very busy and that could slow down some companies as well.

We are arriving on a Tuesday.

Is Amalie a car rental agency?

You should not have any problems on a Tuesday.

Amalie is a well reviewed rental car company. I only rent on STJ, so I have no first hand experience but folks seem to really like doing business with them.

Another consideration if you're arriving during the week, is that a 4:30 flight arrival will necessitate dealing with commuter traffic traveling from town to country which can involve a slow drive. In that respect, a weekend arrival is much faster! All in all, though, as long as the flight arrives on time and you're dealing with a reliable agency (Amalie is excellent, followed by Dependable and Discount) you shouldn't have a problem catching the 7PM ferry. Absolute worst case scenario you can leave the vehicles at the Red Hook ferry terminal and take the passenger ferry over but that's a very far-fetched scenario!

Yes Amalie is a rental agency on St. Thomas. The owners are wonderful people and very professional. That's a busy time so book as quickly as you can.

Have you considered renting one vehicle on STT and one on StJ. The earlier arrival could pick up the car on STT and drive both parties to the ferry. The second rental could then be picked up on StJ either with a rental company that stays late or the next morning. The STT rental will have to be able to handle all the people and luggage though. That should save significantly on car barge costs as well.

You should have plenty of time. I always rent in StThomas and drive to ferry as opposed to lugging bags multiple times. If you flight arrives on time you're good.

Only problem is if plane is delayed. There was a recent poster who had that happen- 4 hour delay and they arrived too late fro the car ferry.