I've had one of these for many years:

Birns & Sawyer Shoulder Support 200016 B&H Photo Video

I'm planning to use it to shoot DSLR video, and I wanted to attach a QR clamp since the camera already has a RRS plate. I order this one:

Screw-Knob Clamp DDC-42i - Products - Sunwayphoto-a superior photography accessories manufacturer in Shenzhen China (http://www.sunwayfoto.com/html/products/201007/197.html)

It's a nice clamp, but the problem is that I can't even tighten the camera screw because about 1/3 of the clamp knob is below the surface. So I either need to extend the camera screw (with an adapter?) and build up the shoulder mount's platform with something like a rubber block, or I need to give up and order a more expensive lever-type clamp.

Can anyone think of a solution that would allow the existing clamp to work? Thanks. (I hope I've made this semi-clear.)

A riser/spacer block and a longer screw would probably be the easiest, unless you can mill or grind the base plate of the shoulder mount to get clearance. I've run into similar "conflicts" a few times, all depends on how much work you want to do, or if you want to mod one of the pieces.

I'll probably bite the bullet and buy a RRS lever clamp, then sell the old one on ebay.