You may have another option open to you depending on the macro subjects..if they are static then using the camera's mirror lockup function (usually found as a setting in the custom function menus on Canon) along with remote shutter release will eliminate the need to touch your camera once setup and positioned.
Mirror lockup does exactly what it says, when you first press the shutter release it lifts the mirror mechanism up out of the way, you then need to press the shutter release once more to take the shot but since the mirror mech has already been lifted this process is now totally electronic and involves no moving parts-thus does not introduce any vibrations at all.
As long as your tripod is not completely shaky this method should return great results out of your existing equipment until such time that you change to your much converted IS lens.
Hope that helps
