A bunch of us are discussing riding property belonging to the "Ross Foundation"...Many on this forum have ridden there. Search for more detailed info on the ADV site. It's Not too terribly far from PB.
Shouldn't be hard to find Paper Land south and WEst of there. There was a Sand pit area back north of PB, off 530, I never been there but I had a few friends that would ride there. Seems like it was in the Redfield area. But I know nothing more about it. Someone else might remember.
I've seen an area near the intersection of 270 and 65 on the north side of PB. Trails running around in the sand beside the road. Never ridden there.