I think the ability to estimate crown canopy would be a good future feature for Assisi. In California, it's a necessary piece of determining CWHR attributes. Assisi takes inputs for calculating crown width, but those values don't seem to be exposed anywhere (correct me if I'm wrong), and even if they were, it'd be a nice attribute to estimate in SummaryByStands. A paper I have been looking at to use is Modeling conifer tree crown radius and estimating canopy cover (2000) by Samantha Gill, Greg Biging, and Ed Murphy (see attached).
Aside from crown width estimates, they developed a calibrator to account for overlap. It's a constant calibration, but maybe down the road we can attach it to between-plot variance in stem density or something.
Modeling Conifer Tree Crown Radius and Estimating Canopy Cover