I would agree that access from Sugar Pine Rd. would be easier. See the following map (Foresthill OHV Trail system map). Trail #4 passes through a portion of the quarry area.
Also, I agree with pushing this off until the roads are in better shape. If I remember correctly, there are markers for snow plows along Sugar Pine Rd. Seems a few of us are cheap sob's, spending money on new guns, ammo, etc, etc, vs buying new tires for our rig's. I've been milking the tires on my Jeep waaay tooo long.