It's product photography.... you have time to compose the shot right and control over lighting conditions. You subject is not moving. Perfect conditions for a macro lens mounted on a tripod.
I'd look at the 100 macro. It is almost as sharp as the L version, half the price, and when mounted on a tripod you don't need the IS and faster focusing that the L version provides. With the 100 macro on your crop body you should get sharp pictures and you can set the lens far enough from the subject that the camera is not blocking the light.
When you go for a tripod, don't let them sell you any of those flimsy tripods or expensive carbon-fibre tripods. You want solid and heavy. Solid and heavy means less camera shake. Also, consider using the timer so that you can reduce camera shake when you press the shutter..... because you are not dealing with movng objects you can drop down to lower iso's (cleaner pictures with less noise) and increase the F number for more depth of field, and this can mean longer exposure times, which is why you worry about the camera shaking when you press the shutter.