That works too. IMO, Sultans will do fine in a mixed flock so long as you don't put 'em in with any game breeds, or breeds that have a rep for being fiesty. At this very moment, our Sumatra pullet is putting our little Sultan pullet through hell and back. We won't be getting one of those ever again.
At least keeping them seperate will make less problems. But go for it. They're my favorite breed. Very personable.