Al and I rarely use chemicals in the holding tanks.
We use blue Dawn for dishes, cause we can also use it safely for the roof and exterior of Tana as well.
I use foaming bubbles for bathsink and tub, I wipe down tub and shower walls with one of those miracle clothes after each shower, keeps the soap from scumming up on the walls and floors, and helps to get rid of humidity asap. Use foaming bubbles for exterior of toilet, and one of those Clorox wand thingys for inside cleaning of toilet.
Kitchen sink (note I have a 2004 unit, not the new sinks) I use a little soft scrub. Rinse well. I cannot instruct on new sinks.
We wipe dishes off as much as possible before washing, reducing food particles in the grey tanks.
We practice, strongly, MORE water, LESS paper, in the black tank. Gently used paper goes in a trash can, just like the boaters used to do.
We clean the interior of the tanks with Calgon laundry additive (not bath beeds). A capful (I prefer liquid, but there is a powder form) in each gray tank and a cap to two in the black tank when we run really helps. I rarely do the Calgon thingy if we are sitting for a while.
We use a water softener, On the Go, very helpful for keeping mineral deposits and crud off the sinks, faucets, and when we used for 3 months straight in the RGV we had (sorta) functioning tank monitors, had not seen that in so long we lost count.
That is probably more than you asked for!
Enjoy that unit!! Safe rides.