I think there are some threads on the Brian Enos Forum for DIY wet tumblers.
Before going bigger I would go to a 2 batch system. A lot more flexibility that way. I have 3 vibratory & find it convenient to have different batches. Plus I tumble lube off at some point after sizing, so that is just a short run in the cleanest media.
The roller systems with 6" PVC can get too big (heavy) to handle according to what I have read. I have used a roller system to tumble case lube onto cases, which is why I made my own case lube.
On the cement mixer you can spray the inside with bedliner or undercoating according to legend.
I do know of 1 guy that uses the cement mixer with a solution. I heard the process second hand from his brother a few years back. The guy & his wife shoot a lot.
Personally managing any kind of chemistry is not something I want to do. I also avoid getting brass wet if at all possible. Wet tumbling sure does do a good job though.