Go to a Suzuki dealership and see if they have a spring rubber isolator. This is the rubber piece above your coils. The inner dimensions of the spacer will be near this, and the outer near the same.
Or crawl underneath, measure the bump stop tube is nearly 2-1/4", and the outer most of the coil is nearly 4". Simple enough, eh? Or was that 4-1/2". Can't remember.
To add, the spacers will have a little lip coming down from the center like the poly's for the coiled Jeeps.