I feel for you but I wouldn't get too paranoid.

One of my mates came round and knowing what he was looking for it still took him a good few minutes to find my 4 ft plant, and my garden is by no means large.

Can't you get hold of any camoflage mesh stuff , I have built a mini greenhouse for mine with a few bits of old wood and some plastic sheeting which hides my plants from prying eyes.