Although baffles in tanks make sense, they wouldn't work very well in waste tanks, and I've never heard of baffles in a landlocked RV tank - even the freshwater. It might be done, but I wouldn't expect it.
I just find that advice totally impractical, it doesn't relate to real life at all. There might be some cases where I might drain off some water if I was heading for a high pass because my truck isn't exactly over powered but to drain the water to empty because I didn't want the water to shift, never.
If it's impractical maybe ETI can explain to you why they put it in the manual. What is said in the manual pertains to avoiding side-to-side sloshing. We find the tow to be noticeably lighter and prefer the handling without the extra 250 pounds over the rear axle when traveling any significant distance. Instead we leave just enough so the pump won't suck air and keep a 6 gal jug in the TV and a 3 gal jug at the rear of the bed.
Trailer: 2009 Escape 17B 2020 Toyota Highlander XLE
If you live on the west coast of North America, or any other earthquake zone, you might want to keep your water tanks full and drain and replace periodically. Water will be handy in the event of an 8.9
What happens to the hole when the cheese is gone?
- Bertolt Brecht