I used some Easy-Off oven cleaner and it took the carbon off, but it also caused the pistons to scale, so it probably did more harm than a wire brush.
I can relate to the solvents. The stuff I put in my parts washer wont cut dust.

I bought a kitty litter pan and a couple of gallons of kerosene and clean up everything that way.
I think that "don't use a wire brush anywhere on a piston" is a load of crap anyway. Steel wire-yes. I have a fine wire brass wheel on my bench grinder and it doesn't seem to hurt aluminum at all. Stay above the top compression ring and I guarantee no ill effects and it will make them look like new.
If the pistons are off the rods, you can put them in the dishwasher while your wife's not looking and clean up a lot of stuff off them that way. (The rods will surface rust).