As I thought more about how to solve my activity data problem in a different post of mine I thought of this. My activity data for my apple watch is stored in a backup that is running iOS 8.3. My watch is now running OS 2.0 and I must have my iPhone running iOS 9 obviously to connect the two. If I continue to track my acitivity data running iOS 9 and WatchOS 2 and later when (if ever) there is a way to downgrade to Watch OS 1.0.1 again could I option-click update and go back to iOS 8.3 on my phone and restore from my backup of iOS 8.3 with that activity data to combine with the days I got running iOS 9? It's confusing and I don't know if it's possible but worth a shot.
Even If I lose the activity data I have in the iOS 8.3 backup I wouldn't mind too much as long as I don't lose the activity data I have everytime I update to a new beta version.