Glad to see Salak Gula mentioned here. Very rare to hear a mention of this amazing snake fruit. I currently grow two plants here in East Bali. I had to plant these seedlings in pots about 4 months ago due to lack of space in spite of my friends' recommendations.
These are used locally for hedges. Thorns discourage trespassers of all sorts. They can grow very big under optimal conditions (tropical with some shading), but take a while to grow. It may be an idea to plant these together with a faster growing hedge plant, say blackberry for instance.
If I needed to grow a vegetal hedge in this climate, I'd probably go with multiple species rather than a single one. Salak, blackberry, moringa, mulberry, passiflora would all be intersticed with leucania and bauhinia in a mostly edible fruit hedge!