By stunted growth do you mean for the first few years or for the life of the tree? And after a few years dont you want a more stunted Jackfruit tree? I am trying to keep my trees like 4 or 5 meters high. I have some that are like 20 or 30 meters and half the fruit or more is in accessible
Edit: Also one other thing I would mention, not sure if it has been tried or talked about on this forum, but there is a guy in Vietnam working with Vetiver grass and he has tried with several different fruit trees, guava, jack fruit and a few others, planting vetiver like 5 cm from the base of the plant when he plants it. The vetiver roots grow super deep and the theory is that the fruit tree uses the deep roots of the vetiver to go deeper. Here are a picture.
There is a user on this forum called Tho Ngo and he has several photos of vetiver companion planted besides a fruit tree, and then a photo take one year after and the fruit trees that have vetiver grass planted besides them are all much bigger than without. Here is a link to one such thread.
https://www.facebook.com/groups/vetivernetwork/permalink/10158382660487760