Cyclops is right, no campsites nearby at all as far as I'm aware. People do still camp under the aqueduct in Muiravonside Country Park. Alternatively, you'd be welcome to camp in my garden. I live about 2 miles from the wheel, but not in Falkirk.
Zep (formally known as RJMcB)
ps. If you're in the area and like odd constructions, you should visit The Pineapple too.