Brakes reassembled, bled, wheels back on, and test driven. Slight rub on front pads and that has already settled. Packed the dog, wife, and I and took a ride. About 3 miles out the driver side rear axle slid out of the housing part way; dual wheels were protruding about 2 feet away from the vehicle. Didn't completely fall off but close as I got over just in time. Tow truck, slowed traffic, the whole works. Not my proudest DIY moment.
Upon inspection, very little damage. Bearing seals are shot, and bearings will be replaced. The locking washer was fastened to the large cylinder that screws onto the axle housing. The lock washer must not have seated properly into the groove that prevents the fastener from unscrewing as I drove. I'm grateful to have not crashed, not injured anyone with flying dual wheels, and to have not destroyed my motorhome. The repair and test drive will be completed again today.