3rd person to 1st person view with two engines

UFPS controls 1-st person camera, animation, AI behavior, scene control, and interacts with all other objects in the scene. We are also using Space Kit (don't ask me why). Space Kit controls 3-rd person, includes a spaceship controller, accounts for zero-g and fire control.

Switching one to the other would require re-wiring the calls between all the objects in the scene, and between the player object and the controller in real-time, possible (maybe) to do, but more work than I would like to take on, not to say that would leave a build riddled with holes for bugs to show up when we least expect, and crash due to a missing null pointer while doing an API call.

I thought an an alternative would be to just pick one engine (like UFPS) and force it to act as the Space Engine, but will require hacking the UFPS engine to do something the other one already does really well.

Another of the solutions we have been thinking is to switch from one engine to the other depending where the player is (ground or space) but we are trying not to mix those two.

I think this is very skunk works, and I want to simplify this process and make it cleaner. Which would be a better way to do this, so we can switch from 1st person to 3rd person easier without having to re-write a full engine?