> I am close enough. Do you think the hassle of remembering a phillips
> screwdriver, and having to remove the hatches with it, would be too much?
> I could always tape a little baggie inside with spare bolts in case I lost
> one.

If you were going to just screw into the beam through the plywood, maybe you should consider using studs and wing nuts? Any decent hardware store has studs with wood threads on one half, and machine threads on the other half. This way there is no screwdriver rusting and rattling around. Spare wingnuts could be mounted on an extra stud in the cockpit.

Good luck