Gimbal to Shoulder Rig Quick Conversion
This would work with any type of should rig. You could use your existing shoulder rig with your battery solution mounted on the back for a weight. Just add a quick release plate to your gimbal and existing should rig.
In my specific setup, I have my quick release plate mounted to the gimbal with 2 screws to a cheese plate. That cheese plate is mounted to the gimbal in two locations. One is the gimbal itselt with a 3/8 screw on the handle right above the gimbal's trigger. It's also mounted to a Smallrig mounting clamp around the neck of the gimbal.
The cheap shoulder pad works, but its by no means a well built product. Its made from cheap plastic that isn't perfectly silent when moving around. Sometimes makes a squeeking noise at the joints and connection points on the shoulder pad. However, there aren't many options out there that include a chest plate as well. This should pad loops over your should with one arm and has a pad to rest downwarn pressure also on your chest. This type of shoulder rig makes it so I don't need a weight on the backside of the shoulder rig. So even though it does technically work, it should be made from a better material. There needs to be more mounting points on the enter thing. But its only around $20, so its cheap enough to give it a try to see if investing in a better should rig is right for you.