The wand is your best bet. We've had several RV's since 1980 and have cleaned each of them at the end of every season with the wand.
You're basically putting a high jet of water inside your tank and washing down all the inside walls, bottom and top. This type of cleaning will also keep your tank level monitor probes clean.
After a thorough washing and drain, we close the drain valve, fill the tank halfway with water, add some bleach, stick the wand down there and let it rip. Constantly turn the wand so the spray goes in all directions, and tilt it so the spray goes up and down also. This will give a final agitation inside the tank. This final rinse out will do wonders.
Putting half a tank of water in and driving around the block is basically useless. The difference is the same as if you filled a bucket halfway with water, picked it up and swirled it around a little, as compared to filling the bucket halfway with water, then taking your garden hose, setting if for high jet, standing two feet over the bucket, and spray directly into the bucket, really agitating the water.