Charouleau Gap used to be difficult and very rutted, but unfortunately the USFS has bulldozed the hell out of it recently. They started last January from the Catalina side and just started again where they left off a few weeks ago. They're probably almost halfway through by now. I've had a buddy's stock 4 cyl YJ on 31s out there recently with no major problems. There are still a few small boulder crossings that might give you trouble, but with a good spotter you'd be fine. We took a stock JK Sahara all the way through about a month ago. For reference, last January they took Kiss Rock, the coolest obstacle on the trail, from this
You'd be fine at Reddington/Chiva Falls, just make sure you're disconnected or you'll have a hard time getting back up Three Feathers. I've run that trail with lots of Jeeps on 31s.