Where do you put your D-rings on your sidemount rig, and why? My Halcyon Contour came with 2 on the right shoulder strap, and 3 on the left one, and they are in odd alignment: bottom shoulder D-ring on right strap, on which I clip the tank, aligns with the top one on the left (and all that, of course, in addition to 2 D-rings on the waist, and 2 rails in the back). They all must have a purpose... the top right one seems to be used for a backup light that is mounted on the shoulder. The purpose of the two bottom D-rings on the left is unclear to me. Other rigs seem to be configured differently...