What can I do about my wild plum infused vodka?

About 2 months ago I started 2 gallons of wild plums with cinnamon, orange peel, and vanilla in vodka. While the taste is good the plums overpower almost everything with their sour taste. I am not sure what I can do better next year to get a better flavor or if I can add something this year to make it better. I was thinking of raisins or figs to make a hybrid flavor but I don’t know if this would be good or not. The only other thing I can think do is sweeten it with a simple syrup and age it longer but again I don’t know if this will do anything