There is not a Police Presence waiting to nab people traversing the beach to get a taxi.
The 4pm weekend closing is meant to deter parties of groups and gatherings in the Covid times.
Without making previous arrangements with a taxi driver it might be a LONG wait getting a taxi at Maho that time of day/weekend.
Having dinner in Cruz Bay is great but I would put the big boat a lot closer -- Caneel,is an easy dinghy ride or maybe use the dock there.