The hot rod 20's like the 20-250 are pretty fun. My 20-250 has an 8tw so I shoot the 55gr Bergers in it. Not sure anything lighter would survive the RPM's in my barrel though.
In all honesty, any kind of "improved" variation off of the 6.5x47 is basically going to equal and be about the same thing as something off of the Creedmoor case so unless you just want to add cost and extra work for yourself, not sure there is anything to be gained there.
I think you can definitely get to a point of to much of a good thing and cartridges become so overbore that unless you are running extremely long barrels, they're at a point of diminishing return. As well as extreme overbore leads to other complications too.
I'm obviously partial to the 6-284 because I have one, but for a wildcat hot rod cartridge that "checks" just about all of the boxes, the 6-284 is hard to beat.
Also, be aware you'll hear all kinds of crazy velocity numbers thrown around about how there this or that shoots these blazing fast speeds with substantially less case capacity/powder and I don't doubt some get those crazy fast speeds, but they're also doing so with crazy pressures too. You can't hot rod the bejeezus out of one cartridge and not the other, then crow about how much faster it shoots.