If you were to do single BEL morph (let's just say Mojave for an example) + Clown x your Banana Butter, keep in mind your odds are that not all of those will be easy sales.
Mojave Clown x Banana Butter male maker:
Male Banana BEL het Clown - easy sell
Male Banana Butter het Clown - relatively easy sell
Male Banana Mojave het Clown - relatively easy sell
Male Banana het Clown - relatively easy sell
Female BEL het Clown - easy sell
Female Butter het Clown - tough sell
Female Mojave het Clown - tough sell
Female Normal het Clown - near impossible sell
+ very low chance for Banana to crossover and give you any of those of the opposite sex
By using more complex animals with more complex ID's, you have a lot better odds that most will be easy to sell, even if you end up having to sell some for cheaper because you aren't 100% sure on the ID.
On another note, if you put too many different morphs together they can really go overboard and kill off interesting colors and patterns, but with the exception of BEL (which intentionally kills it all off), the morphs I suggested for a mate for him would go really well together without taking too much away. Enchi and YB will really enhance Bananas and bring up the quality of color, especially making them stay nicer colors as they mature. When you combine the right things, it really magnifies the quality of OS from veyr simple morphs.
If you really like Clown, I would highly encourage looking at a lot of combos to see what morphs work very well with it. If you want to make Banana Clowns, Enchi and some YB morph would really put it over the top with screaming oranges.
Some examples:
Enchi Banana Clowns
Banana YB Clowns:
