Zanthoxylum rhetsa is usually propagated by seeds. The seedlings are tall. The management practices including harvesting have limitations for tall canopy. The canopy management will make this spice more economical.
In order to keep the fruit clean a cutting tool with a bag attached to catch the cut product could be constructed. Bag would be wired open and may be able to get 2 or 3 bunches before bringing them down. Or you could create a sock so the fruit falls through it into a basket on the ground.
Most plants, once they reach bearing age, can be pruned to keep the height much lower. You could try with these as well. You would need to note if the flowers are produced on old or new wood and time pruning appropriately.