Run&Gun
Veteran
Eric, look at the Zacuto VCT Pro. Sliding, extremely low-profile baseplate that mounts to the camera that allows it to mount and adjust fore and aft in the Shoulder mount for balance and they have a stand alone piece that they call the tripod doc that also accepts the baseplate so you can mount the camera without the shoulder mount. B&H is actually offering the Pro wth the tripod dock thrown in for free right now. I thinks it's designed for exactly what you need and want to do.
https://www.bhphotovideo.com/c/product/1288913-REG/zacuto_z_vct_p_vct_pro_baseplate.html
https://www.bhphotovideo.com/c/product/1288913-REG/zacuto_z_vct_p_vct_pro_baseplate.html
