There is nothing prohibiting you from booking your accomodations or airline flights. You can do that at any time (although you are cutting it close). If you wanted to book a jeep you needed to do that yesterday. I would call all the rental outfits on STJ tomorrow and see if one is still available for your dates.

You must have a negative COVID test taken up to 5 days before arrival, or a positive antibody test, and must register on the USVI travel portal to allow entry. https://usvitravelportal.com/

It is now unclear if you will be required to have a negative COVID test in order to be permitted to re-enter the US. https://www.cdc.gov/media/releases/2021/s0112-negative-covid-19-air-passengers.html If you do, then you will have to obtain one in the USVI three days before departure.