OP, I think you'll have adequate clearance with bike configured as described even on fire/gravel roads.

As another has suggested, tires larger than 35mm would be nice in rough if you have tire clearance, which you should on a 29er MTB.

Even on low BB height bike (~260mm), I would experience pedal strike very infrequently while pedaling through a tight turn with bike leaning quite a bit, effectively shortening distance to roadway surface, with 175mm cranks.