Cervelo P4 - saddlebag replacement with integrated water bottle?

I am looking for an aftermarket (or from Cervelo if they make them) replacement for my P4 integrated water bottle, so that I can use it as a replacement for a saddle bag. I have seen some pics where owners have taken the factory bottle and sliced the top to make an opening, but it’s not the best looking workaround.

Has anyone seen anything? Ideas or thoughts? The bottle holds so little water that as previously discussed, it is fairly useless for that function.