I rode ~15 miles of loose gravel forest service road on 32mm Pasela TGs during a 300k brevet last summer. A crushed stone path should be no problem for just about any 32mm tire. Definitely no need for something as aggro as the SB8, especially since you're doing a fair amount on the pavement.
If you want something with some extra cornering lugs and a nice ride on the paved parts of your commute, check out the Conti Travel Contact in a 37mm.