I believe you just have to check for name uniqueness. Both feldmap and badosu maps define their own balancer which they only use in their own new maps (thus unique). So the only way they would be incompatible is if some functions defined share the same name in both mods, then one would override the other which is bad. With a quick check it seems there is no shared name so they should be compatible but tell me if you see otherwise.
A way to check for OOS if you are alone is that you can launch a game, generating the map, then exit, change the mod order, and open the replay to that game. If it is incompatible you should see OOS there.