I would not guard the Memorial with ceremonial guard, especially having borne witness to the gong show that exists at the governor generals residence, where the GGFGs require guarding themselves to prevent tourists from touching them and their weapons.
Make the guard a platoon of Cbt Arms troops in Cadpat, perhaps with an identifying armband. With a shift rotation, you could have 3-4 on duty 24hrs a day. Goodwill ambassadors and question answerers by day, idiot stomping ****kickers by night. I'd volunteer!
I echo the sentiment to the effect of how we spend far more on other things - like sending troops to do ceremonial guard at Buckingham palace, and hundred - man honor guards for generals - while leaving the War Memorial undefended.