Mendocino - Big River Trail conditions?

Will let the locals respond, but I would guess the gravel goods will be fine. Probably biggest concern is downed trees and closures due to any logging activity.

if you’ve not ridden up there before, I suggest you make sure you have a good map and/or gps. Phone is not likely to be reliable at times. Also, be prepared for the unexpected. You can get yourself way back into those woods and it’s a long walk out (no phone service). For example, I always carry a spare der. Hanger when riding there and a chain tool.
would also suggest the widest tire you can fit, it will make the gravel bike more fun IMHO.

PM me if you want some route suggestions.

Yes. It will be good to go. I rode over there last weekend. All of the trails that I rode (besides Shithole) were dry. That trail is usually a sloppy mess in the winter, so it being pretty close to dry, gives it a pass. All of the logging roads were good as well. The top of Manly was a little dusty...