I didn't change any of the directories where the services reside, so all the URLs should be fine (10.x is not included in any rest service URLs). I didn't end up needing to test the dummy layer, but thanks for the suggestion. I ended up doing this:
I did do a backup/restore, but the restore failed, so what I did was run "Repair" on the ArcGIS Server program, once I did that, I was prompted to build a new site. I created the new site without having deleted my arcgisserver folder so the new site maintained all my services/users/roles (I think that's why, not 100% on that). When I created my new site, the connection with the web adaptor disappeared obviously, so I re-configured that and my services started showing up again. I'm really not sure what went wrong to begin with, but I'm happy it's working now!