After a lengthy google search, I found that IMS RC9 doesn't work for Orbiter 2016 and that IMS 2 has been abandoned. Is there a way to fix this, or another mod that adds more engines to something like SSBB?
There is unfortunately no way to fix IMS for 2016 without considerable effort, and there's no way to finish IMS2 without considerable effort. Effort I simply can't spend at this point in live. So no, there's no help on the IMS front.
You could always velcro your engines to whatever it is they need to move, though controlling them might become an issue...