I recently decided to swap out my tote bag for a backpack and settled on the L15 for EDC. Love, love this bag, except the water bottle issue. The inside sleeve doesn't work for me due to my A5 Roterfaden notebook/brain which goes with me everywhere. That plus a couple of pouches make the sleeve unusable. What are my options for hands-free water bottle carrying? I have an insulated Kleen Kanteen.