Most individuals can use the same tanks (as outlined by what many have posted above). Especially if using a BP/Harness/Crotch Strap setup. In scuba diving we typically 'overcorrect' the wrong problem. This is a simple case of this. Adjusting the crotch strap and shoulder straps of your harness will cover 99% of your 'tank problems' from hitting your head on the isolator (ease off on crotch strap...possibly let out in shoulder straps...should be able to get three fingers under it on each side). If you cannot reach the valves crank up on the crotch strap. Treat the 'problem' not the symptom. Do not lower the bands.