Its possible, but not advised. They will interbreed and then we will eventually not have two different types. Also, CH seem to be more aggressive at least some of time, from what I've read here. Of course this varies with the individual tortoise.
The market, at least here in south Florida is flooded with hybrids bred for more color because color means money.
I would not encourage the practice.
In a very large outdoors enclosure you could attempt an all female group like mine with a few Cherryheads.
But like has already been mentioned, it's not guaranteed to work.
It's best to have a separate pen for each sub species.
Mine are all northern btw.