Brad if you have not mounted the engine yet. I like to use it to help set the CG. I put everything in the plane except the battery pack and engine. I turn the plane over on the CG machine and set the engine(with muffler,prop, and spinner) on the bottom of the mount. Then set the battery pack where you have a good spot. Then the engine can be slide slightly forward or aft until you achieve the CG you need. Another way would be to thin CA the engine to the mount with the spinner clearance you described above. Then point it on the CG stand and find the CG with the battery pack. If the pack needs to be way forward or aft, then pop the engine off the mount, re glue in a better spot and try again. I am not bragging but I have about 15 planes in my shop and there no lead in any of them.

david