Getting UE4 4.16 Game on Steam

We have a game that’s built in Unreal 4.16, and we want to post it to Steam. However, the options available to us don’t seem to work. We tried to upgrade our game to 4.22, since that’s where all of the Steam features are, but unfortunately so much of the core engine was changed that our game is not compatible with it, producing countless errors. We also tried creating a new project in 4.22 and migrating over our assets, but it also had numerously problems and errors. We could just go and tackle the errors, but honestly at this point there is no guarantee it would work and we’d be better off starting over from scratch, though we’d like to avoid it.

Is there a way to get our 4.16 game on Steam, or are we stuck? Is there a way to post it up to Steam and skip the Steam SDK/Steamworks altogether?