I sling all my bottles from 19 up to 40 cu ft. I used a backmount and simply did not like having it out of sight. IN addition having been taught to charge the system before entering, then shut it off, then again at the turn point, and finally at the beginning of the ascent having my left hand just be able to drop on the valve and know where the reg is without having to waste money on a new computer with another transmitter that may of may not work would be too much hassle. For 25 bucks I bought enough rope, and fuel line to make three sling setups and still get 2 SS bolt snaps. Having a slung bottle also eliminates another thing to get tangled up that I could not reach without a degree of difficulty that is not there with a slung bottle. Finally I'm not clear on what the OP's final intent is with this but it is not a way to deal with poor gas management and dive planning that should be used first and foremost.