Route the 5' as has been already described here. Route the pony hose along the tanks between the tanks and your BC. Bring it over your primary tank over your right shoulder and to a bungie. The 5' hose will be routed around your neck after you bungie the pony hose so there is no interference when donating. I don't dive this configuration, but it's similar to if you were diving doubles. The bungied reg comes off the left post. The only difference is your pony is upside down, so you have to route the hose up that way. I'm guessing you'll need a 4-5' hose for the pony. You might need to get a custom length. If so, check out TDL. They can custom your hoses.