I don’t monitor root temp either. Mine is in a pot, mostly kept outside. In 8a GA, it’s plenty warm in the spring/summer/fall. This winter, I’m going to try leave by it outside and dragging it back in when it’s supposed to frost. I kept it inside last winter and didn’t notice anything in particular. It didn’t seem happy or sad, it just kinda sat there till I put it out again.
But my goal is not to have the best/most productive tree ever, just to keep it alive and enjoy what I do get. Sorry I couldn’t be more help.