You can do it on the Mavic pro. I have one with an analog camera glued on it. the Phantoms used to be able to , until the phantom 3 - I think. As stated above, I don't think it will initialize without the camera check BUT No harm in trying just pull your gimble and see if it will start. If you do get it to work you will only have ATTI mode so takeoff the first time with care.
I would ask why? If you want a "fly around for fun" drone, I can name off quite a few that wouldn't cost a lot and you wouldn't have to jump through hoops to get it to fly.
Let us know how it all goes !
If you are very determined I would tell you to visit some Drone Building Forums for details.
This is a great forum but you need more "Builders" advice and you might have better luck there.