I did this exact mod on my Elite bottle to hold a spare tubular.
I cut a long slit with a Dremel on the underside of the bottle, and thus from the outside you dont see any modification. I can easily spread the cut edges open and get my tubular in/out as needed. I actually did have to use it for a flat at IM Vineman last year, worked perfectly!

CANT UPLOAD PICS due to size of files. PM me, and I will send you the pics of what exactly i did.

---

Team Zoot-Texas, and Pickle Juice