FWIW, I drained, did a fairly good outlet end back flush and a built in flush. I then added about 5 gallons of water and about a cup of Rid-X then drove it home, sloshing around, 109 miles. Currently the RV is sitting in the driveway with a 'percolating' tank for no better term. When it stops raining, I'll do a final drain and flush. The Rid-x appears to be a bit stronger then Happy Camper and available virtually anywhere for about 12 buck a box which will do a 1500 gallon septic tank
(I can hardly wait to fill a bunch of 5 gallon buckets to drain in the S&B toilet
)