I'm not fully decided on how this unit is going to attach/dock with the main cabinet base, but whatever I do it will be easily removable for service, adjustment, cleaning and moving.
The quandary I am chewing over is one of vibration/shock and alignment. Because I'm working with extremely tight tolerances to get the maximum picture size in the smallest space, changes of angle or position of the projector as small as an eighth of an inch are enough to throw the projected images out of alignment. Also impact/shock and vibration could be an issue with hot projector bulbs breaking. Combine those issues with a style of machine that requires a bit of slamming and banging to play it properly and it causes some design headaches.
I'm still thinking over PL1's suggestions for a dynamic tilt built into the lock down bar area to minimize vibration through the cabinet and generally reduce the abuse the frame takes, not to mention the transmission of shock into the projector housing etc.
I may try keeping the housing completely separated from the case, just have it lifted into position under the cabinet. This way there's no chance of shock transmission and the cabinet will be heavy enough that it should stay put even with moderate to heavy nudging. Sure there may be a small chance of the cabinet moving out of alignment but it's an easy fix to realign and avoids the other risks of damaging the bulbs.