Lucky you! I love persimmons.

Your local County Extension Service will probably have a whole pamphlet... with recipes... to either give or sell to you. They are a good resource for such local produce.

UCDavis has an article updated just a couple of weeks ago about preserving persimmons. At the end, there are two approved recipes for jam (rather links to those recipes). One is a freezer jam and the other requires calcium water, not sure if either are what you were looking for.

UCDavis.edu Persimmons

I found that article, but I prefer to do a recipe without pectin and we don't have room in the freezer for jam.

Low acid or not, jam is so high in sugar that it's safe. The clue is either to process in a hot water bath or to be VERY sure everything about your jam and jars are absolutely sterile.
Acid is needed for pectin to jell, but if you aren't using pectin you will either have to add a natural source or just cook the fruit so long that the liquid boils off and it thickens to be jam.