This. Right. Here.
I wouldn't waste my time trying to prove out possible hets with only a het female to my name. You will very likely spend several very frustrating years holding back and then trying to prove out all of your possible het Clown males with only a single het Clown girl at your disposal. Even with a known het Clown x het Clown pairing, the odds are only 1 in 4 of producing a Clown. It would be perfectly normal to not hatch any Clowns at all for a couple of seasons even when you know both animals are hets.
It'll be a little more expensive up front, but trust me - it'll be so much more worth it when the hatchlings you produce from your CG x Clown pairing are guaranteed het Clowns you can breed back to their momma for a guaranteed 1 in 2 shot at clowns the very next year.
Good luck!