But soursop is a good sized tropical tree. Are you sure it's do-able?

A really big tree, 30' plus. Cultivation and flowering are tricky even in soil culture with good drip irrigation and it takes a number of years for trees to flower.

I have experimented with Cherimoya & pawpaw which is supposedly related to the soursop. My pawpaw did OK, but my baby Cherimoya did not last long. At the time I used a flood & drain with Perlite as a media & a general all purpose nutrient. If I did it again, I would use a pot culture, a drip method, a neutral media which did not degrade, & a nutrient that matched the needs of the crop. Supposedly there are dwarf varieties of sourop which might be better than a full tree. Or, you might use hydroponics to propagate cuttings & later transfer them into soil.