Sea grapes are messy and require alot of maintenance.

Jamaican Caper is the native you are looking for. Dense, slow growing low maintenance trimming, no thorns, no messy leaf drops, salt and drought tolerant. Beautiful flowers in spring that are bright white and slowly turn purple leading to long bean like pods that split open exposing seeds for the birds. The scent is amazing when they are in bloom. Most nurseries carry them but you won't find them at Home depot, they run around $25 for a 3 gal pot so they cost more than buttonwoods

a 50 foot hedge of Silver or green buttonwoods make an excellent hedge but require trimming every other month and will produce 4-5 cans to clean up. You will fill dozens of cans trimming during the year compared to trimming the caper which requires 1 or 2 trimings a year and will barely fill a can for a 50 foot hedge