I use mine similar to that but each has there own bridge. One is adjustable. That way I can keep it low or move it up higher on my back and adjust it. I like it but I kind of like the way the back band for the Kestrel has prusik on the bridge to allow you to slide it up and down. Imthere is doing something similar with his ernies outdoors linesmans belt.
I think any time you can add surface area it's going to have less pinch. I'm not sure using one bridge will work like you want it to. Seems like they would either want to pull back together or spread even further apart depending on how you had them spaced. It's worth trying since you would have one less bridge in the way. Depending on your size a second may or may not help you that much. Get one and play around with it. Even if you decide to only use one I don't think anyone could have too many of them.I
I was thinking of adding a second sit drag but more for comfort to reduce stress points or hip pinch. kind of similar to an Anderson Sling. Not sure if it would make a difference though