Just got a brand spanking new CZ-21 for Christmas. Well actually about a month after Christmas after the Boss (the Mrs) approved the requisition. Been wanting one for a while now and she finally agreed.

Had it out to the beach a couple of times with some good results but clearly going to need some type of harness/belt, something as I find the control box mounted on the shaft a bit heavy for my taste. Any suggestions or recommendations?

I got one recently and thought the same thing after the first day of hunting my arm was so sore.

I put it on a belt and it works well.
I found this video that helped me decide.
https://www.youtube.com/watch?v=VTJlSLvPzyM

Tried the chest harness and found it lacking in padding for the shoulders and could not seem to get it positioned right. Kept riding up my shoulders until it cut into my neck.

Quickly went with a belt but had problems finding the right belt until I pulled out one of my old scuba weight belts and mounted the control box that way. Works great. Problem solved.