I was thinking about creating a drum map that assigns all midi notes to 53 Ride bell b/c it has a tight transient and then freezing the track and enabling AudioSnap but I figured I should post on here and someone can confirm if what I'm trying to do is possible or tell me the page number in the manual or what to search for in the help file.
Yes, it's possible to do this. Once you have the track bounced to audio, you can use Audiosnap's Set Project from Clip to set tempos. However, Set Project is not as precise as your manual method, both because the transient detection can be imperfect even with the right sound (something shorter like a cross-stick would be better), and because the calculation of tempos can be a little off.
Also, I would recommend setting tempos only from a single part of the pattern, like the kick, and only setting on tempo per measure unless there's a ritardando/accelerando that has to be mapped to make intra-measure beats fall in the right place.
And finally, due to the amount of tweaking that may be necessary to get the Clip Tempo Map massaged so that Set Project works correctly, it can actually take more time to do it this way than by using Set Measure/Beat At now, especially if you're already proficient with that method as it sounds like you are.
You might also want to look into using Fit Improvisation with a MIDI reference track extracted from the MIDI drums, but it requires a MIDI event on every beat which is not always easy to come by. Some like to record their own reference track while listening to the playback, but my feeling is that this just introduces more timing discrepancies because the reference recording will not perfectly represent the original performance. It might make sense if you only have an audio performance to work from, but if you have the original MIDI performance available, it's best to work directly from that.