In that case I would hold back a Spider Het Clown Male, by the time she is ready so will he. This will allow you to shoot for Bumblebee Clown in no time. Even in that case holding back 1 or 2 females Spider Het Clown can't hurt if you have the room, you never have enough female Hets.
If you don't want to keep a male you can hold back some female Spider Het Clowns instead and pair the Clown to your Pastel Het Clown and hold a male later own from that clutch (if there is a male) it's the longer route but with better odds but if you don't produce male Pastel Clown it will be an even longer route.