I only carry water, I've the red Viper water bottle that we got at VOI6. I went into a cycle shop and got a anodized aluminum water bottle holder bracket (for cycle bikes that fix to the frame). I fixed it behind my seat using one of the existing trim panel screws. Holds it firm, and can be got at when driving, by reaching back over my right shoulder to grab the bottle, and just drops back into place again. Flip top on the bottle ensures no spillage. If you drive with your seat right back as far as it will go, don't think there will be room though.