As mentioned above, and I'd add look for nice fairly flat areas near the water, look for places you would think would be a good place to set up shop for a while.
Also, consider walking the creeks and gravel bars.
Whenever I pass through that area I think of buffalo jump places. Maybe you could talk to some ranchers and get access or pick their brains.
Along the Arkansas or the other rivers in Southern Colorado would be your best bet. Indian Springs by Florence is a nice area but hard to find points. I have been tempted to walk the roads out on the plains where they might have cut through a camp site. Good luck!