You have several wildcat options as already and I went through what you're going through about 4 years ago. I finally settled on the 6X47 Rem as my cartridge of choice since my ultimate goal was a walking varmiter. Looking back I'd do some things differently, first is I wouldn't have used a slow twist barrel, I saved $100 and 14 weeks of waiting by using a 1:12 twist barrel that the maker had in stock which limited my bullets to sub 80 grains.
Next I would use either the .223 or .204 case instead of the .222 RM. Remington is the only one making the case and only in seasonal runs. Remington's brass is adequate there are much better brass choices for the .223 and .204 cases. Plus dies are readily available for either cartridges as well.
Now what I like about it is that every load I've tried in 60 to 70 grains usually goes around an inch and with a little bit of tweaking I can get most under ½". 80-85 grain bullets I haven't found a consistent 1" load yet. I haven't messed with 55 grain bullets as I run that weight in my .223's. So far the 70 grain Noslet BT has been my go.to bullet for prairie dogs to pronghorn. My longest kill to date on pronghorn buck is 305 yards. I have to be a little more discerning with my shots to avoid shooting through the shoulders but I just think of it as long range archery. If I could use a bullet like the 85 grain Nosler Partition Cornell Barnes 80 grain TSX I wouldn't hesitate to use it on deer.
If you feel that you need bullets heavier than 85 grains to kill deer you might want to considered the .300 Whisper or AAC Blackout. If you go with heavy for caliber bullets in a small capacity case you run out of powder room fast trying to get them to feed from the magazine. Plus another thing to remember with these cartridges are for sub 400 yard shots.on anything larger than a coyote.