We only use our camper toilet for urine and some dishwater. Paper goes into a basket, and we do our solid toilet at other places, like the campground toilets or public restrooms.
We took all the comments into consideration and have found that in our 20 gal holding tank that we empty about every 4-5 days , even in warm weather, about 2 cups of bleach and 1/2 lb of baking soda with 1/2 gallon of water keeps it as well as any commercial stuff we've ever used. We emptied the tank, rinsed, poured a bit of baking soda into it while winterizing this fall, opened it a week ago, and it still is fine.
I don't know what this concoction will do to the seals. It's still OK after about a year.
As for the urine = ammonia then ammonia + bleach = toxic fumes, we never found that happening even from the inside of the toilet or from the air vent when we walk into the back door.
Here is a picture of our little motorhome. It has about 130,000 miles on it now and has been in the alll 48 contiguous states in 12 years. https://www.facebook.com/photo.php?fbid=2451849392087&set=a.1184685993794.20516.1727581292&type=3&theater
This was taken at Letchworth NY state park 2 years ago. If you want to mess around on the Facebook site, I think it is all open to anyone.
Thank you for your help.
Please remember this is anecdotal results for us; not long term research.