Thanks for the suggestions Aaron and Alison.
I plan to add some “max velocity” intervals, as Richard Diaz calls them. Where you slowly accelerate up to the maximum velocity you can maintain good gait (maybe 200-300 meters). Once something falls off (SPM, arm swing, over striding, etc) you slow down down to recovery. These are similar to your suggestions and I want to see how they go.
I mostly get sore after generating power in dorsiflexion, either a lot in short time (hill sprints) or moderate over longer time (AnT runs). I can usually recover from the moderate in 24 hours though. I don’t get sore “running” mountains, it’s all the road and flat trail work I do during the week.