There are many ericas (heaths) that grows in warmer climates. Heather (calluna vulgaris) grows best in zones 5-8. You can plant it in any well drained acidic(ph 5.5) soil. You will have a hard time getting it imported to the Islands we no longer ship there. If you have any more questions please do not hesitate to call.

Here is a link that might be useful: Rock Spray Nursery

Erica persoluta, often called Spring Heahter is grown as a blooming potted plant and sold at mass market stores and grocery store floral departments. You might try looking there.

Some of the South African heaths are grown in Hawaii, especially the parts of Maui (?) around 4000' that have a quasi-Mediterranean climate. They are much more exotic than the ones native to Europe, but you might find one that would resemble the North European heaths. Not sure if they would work for you. Erica persoluta is one of those.

Forms of Erica arborea are native to the highlands of Ethiopia. Good luck finding seed of those! And they grow into huge trees but their foliage is still heath-like. That is an amazing plant which ranging from the Pyrenees (provenances are zn 7 hardy) to the Macronesian islands to the highlands of central Africa.

There would also be the native Hawaiian mountain shrubs with a heath-like general aspect, these could be planted as companions to true heaths (like the South African ones) if nothing else.

The Cape has a positively enormous number of plant species, there could be quite a number of Cape heaths to play with already being grown in parts of Hawaii. Or, it may be possible to add to the list - check with state agricultural authorities.