I often get remarks from divers inquiring about my SE500 side exhaust regulators. I’ve always been a fan of this design, having owned similar Oceanic Omega regs since the late 1980s. Rather than clipping the regs in place, I store them in a bungee loop on the shoulder of my SMS75 Sidemount Harness. They are quick to deploy and lay very flat. The purge will never activate in high flow caves and they breathe like a dream.
I’m a fan of upright SPGs as long as they lay snug against my chest or are nestled against the clavicle region. Tank valves hang in place in the bungee loops without the need for a clip. I add a safety clip around the tank neck for deep open water applications. My tanks fit inline with my body with the top of the valve right in the armpit. Streamlining is maximized and range of motion is fully optimized.
You might notice that I have two very small weights on the shoulders of my harness. I could get away without the weight in Florida’s fresh water, but it really helps nail my trim just right. 
