I know a guy growing (and fruiting) Bael in a greenhouse in Bakersfield.
We used to grow bael in our homestead. This is a type of fruit that no one care to plant a tree and no one offer a prime location for this tree. Our trees were huge, and you need big tree for a significant harvest. You have to wait about nine months after flowering to have mature edible fruit at winter. Uncracked fruit stored well for couple of weeks. You have to consider one third to half of the volume of a fruit to be wastage because of outer hard shell, long-thick thread like fibers, top to bottom veins filled with ‘messy glue’ and seeds. Extracting flesh is a kind of ‘messy’ work.