No need for toilet bowl brush ?

I would avoid using chemicals and just use the 'ol tried and true brush method. One problem with the chemical idea is that "stuff" can be stuck on above the high tide level. One method of rinsing off those nasty skid marks is installing a hand sprayer like in the photo. Tap into the water line at the back of the toilet, add some flex hose, a valve and a suitable sprayer. A bit of googling will give you some ideas. This can also be used to add water to the black tank to top it up just before dumping.

Dometic has a complete hand sprayer kit as in the 2nd photo.

We ordered a porcelain toilet for our new TT and it is waay easier to clean than our old plastic one. That's an option, but not a cheap one.

Or... You *could* do as one forum member posted a while back - just don't use your black tank and go to the CG washroom building instead. No obnoxious odors and no tank to dump. :C I guess if you were dry camping in the wilderness, it might be hard to find a suitable log along with some privacy. :(

keep a spray bottle of Lysol near the toilet. A few squirts of a straight stream and everything is removed from the sides. Save on water if your dry camping also because you flush less and don't have to use a water sprayer.