[donger]

I would just call this river donk. If villain has even a shred of hand-reading ability, he has a good idea of our hand, and is betting into you anyway. This is either a desperation bluff or someone hoping to three-bet. Either way, calling is probably best.

Also, re: raise-folding the river, I hate this in general. To paraphrase Clarkmeister, if your plan involves folding, find a better plan.