We used to spend a Saturday afternoon working on a 12x12 gong at 100
(+-) yards mostly off hand, or on one knee - sure you can hit it, even repeatedly, but there are days where there's "just isn't happening" in the air - I think your set up would be a fun challenge but perhaps the volley and step back idea from Bigsmoke would be more fun, for that 8" gong, say 50yds,75yds,100yds etc until there's an elimination.
We'd just shoot for bragging rights who could hit the gong the most times in a row, most times that day, and although nobody ever did it, who could hit and not miss all day - but either way it's all in fun!
I think if you have a person able to hit and repeat 5 times, at 200 yds, on an 8" gong, off hand that shooter truly deserves a prize!