Any recommendations on proper spacing to grow as a wall/hedge along the street? Any other recommendations for a privacy wall that will survive salt spray and summer heat coming off the road?

I've never have grown it. Seen it down in south fla though. found this on youtube:

It has suddenly become popular in Vero Beach. It makes for a big, thick hedge. Probably not very cold tolerant. It should be good for spray.

Jamaica caper is probably hard to get in numbers large enough for a hedge, but it takes very well to being clipped and can be kept at a good size. Fla. Native Plant Society