For research I would definitely go for niche conferences then. APA is frankly embarrassing as a scientist. Its a bit outside my field, but I think ISTSS is a big trauma one. I don't know for forensic work, though some will depend on your exact focus within forensics. There is plenty of forensic-ish work at substance use disorder conferences, but that is of a very different nature than someone working clinically with psychopathy, etc.
Wis and I are likely to disagree on this, but I wouldn't bother with a state org if research-focused. Nothing wrong with doing some networking or popping in to a conference up the road (i.e. you don't need to explicitly avoid it), but there are much better places to focus your time/energy. The conferences aren't going to have much in the way of "A+" work you want to model and the number of people with similar interests is going to be negligible. I might make an exception if you were extremely geographically restricted and simply COULD NOT move out-of-state for whatever reason.