Carol and I were the ones who checked the roads while doing Rusty Blackbird Sureveys: you can get as far as just before the boat launch at Scott Bog. You can almost see the water from where the bridge is out, so it's quite close but there is little to no parking since the lot itself is cut off.
We also found a route that goes around the back way to East Inlet Road, if you take Magalloway Road then Smith Brook Road you can take that all the way through to East Inlet. You will need 4 wheel drive and good clearance, and it adds an extra 45 mintes minimum to the trip, but it is still technically vehicle accessible.