Barry Welling at Vermillion Falls, April 2011
This is a downstream reference gauge, below other forks, but if Big Walnut is way up, Vermillion Falls should be worth a try.
It's a very bony run, so higher water is better, within reason.
Private property all around. Use road access, or ask directly for permission to cross land. The upstream bridge has a radio tower at the corner, and the downstream bridge (which has a horse fence hanging from it) has a decent corner river left. There is fun water all the way to the little lake, so it would be worth parking as close to the lake as you can get and still have an easy walk out.