That's exactly where I cut mine. I've notices that others said they cut right where the clear and black meet. I do NOT recommend that. Yes it'll work, cause obviously it did for them. However, if you cut where you have marded, it'll make sealing them so much easier. The clear plasit is sandwiched by the black, so if you cut where you have indicated, you can remove the top piece of the "sandwich", then cut the clear (if needed) and break the seal from the clear and the bottom piece of plastic. When it comes time to re-seal, just glue ontop the glue, then silicone. Since you'll have removed the top piece of plasitic there will be an obvious void that needs filled, and you're done. If you need more clarification, do not hesitate to PM me.
~Eric
