I use an aero bag by camelbak 1.5 liters with a military insert that has a longer hose. I strap it behind the seat with velcro straps (put behind the seat cushion, held in place by the sticky tac of the velcro strips). These can be bought at Lowes in really long strips, cut them to length. The first strap is at the shoulder level and hooks under the reservoir cap on the camelbak to keep it from slipping down. The lower velcro strap (at your low back level) is threaded through a tag on the bottom of the camelbak. This sinches it up to the seat and keeps it off the wheel . The lower strap will also add as a tacking point for the longer hose. I bought smaller velcro straps with adhesive backs and tacked it on to the end of the hose. This will then attach to the lower strap and keep the hose in place. All I have to do is reach down, grab the hose, drink, and replace. Very easy. As for the shoulder straps of the camelbak, I criss cross them over the headrest. This takes up the slack of the straps so they don't flap and will also hold the camelbak up. If I can figure out how to post pics, I will. My sig picture has the camelbak attached to the back of the seat.