I've paddled the Batsto and Mullica many times myself. One trip I like to do if I want to only take one vehicle and not retrace any of my route is to start at the Batsto millpond put-in, portage around the sawmill, then go downstream to the Forks. I then paddle upstream on the Mullica, which is easy to do on that stretch due to the slight current. You can finish at the put-in on the south side of Rt 542, and walk 10-15 minutes to your car where you started. Part of the sretch on the Mullica has streamside homes on it, but it's still an interesting paddle.