So many options on a Mark 1. I can also stow mine under the cokpit seat on the port side. The lower board sits inside the top board and the bottom of the top board rests above a timber bracket at the aft end of the berth. The top end sits snugly against a piece of curved timber under the bulkhead with a simple wooden twist handle to hold it in position.
In practice I use the starboard locker. Dead easy!
Sean
Azzura