Maybe if the piston has the room for it you could cut a ring groove in it. Or why not make a aluminum piston and put in a piston ring.
I got to thinking about cutting a ring groove in a  few pistons for some DEEZIL engines I have and either making or get made some piston rings to fit and see if the engines would run OK or not.  As it is the pistons are a bit too loose in the cylinders. The Deezil engines have really tall or long pistons, one could likely put on two rings on them if they really wanted to. 

You know, the Russians are getting really good with ceramics. They have been making ceramic coated cylinders for engines for a while now, but I was surprised to see they are making ceramic wrist pins for the engines now too. The Cyclon engine folks are the ones doing it too with their engines. I wonder how well a ceramic piston would hold up.

Wood piston. That might be interesting. Maybe use some of that really hard wood that comes out of Africa or someplace, and soak it in superglue for a while to maybe toughen it up even more. or maybe pressure inject it with high temperature epoxy resin.