Kevin:
When using an elevated safety platform that has been "specifically designed" for that use on a reach truck, the reach should remain in the retracted or stored position, never with the reach extended out.
A safety platform should not catch on the fork arms; I don't completely follow this comment.
You are correct, reach or sideshift should not be used once the person is in the platform. The reach is retracted and sideshift placed in the centre before the person gets in the platform.
Tilt: the forks are made level before the person gets in and the tilt is no longer to be used while the person is in the platform.
Cage won't fit between the fork arms. I presume you're speaking about the straddle legs. In this case, if the platform is on the floor, the driver extends the reach, inserting the forks into the fork slots, raises the platform higher than the straddle legs and then retracts the forks/platform to the stored position. Then the person can get in the platform.
Hope these opinions might be of some assistance to you.
Garry