Think simpler.
To make a pastel super enchi spider clown, RD would have had to pair up two snakes that were both enchi and both a minimum of het clown, plus one of them with pastel and one with spider. This just doesn't fit the time frame. The odds of hitting a super enchi pastel spider clown with both parents only het clown are 1/64. Take out the spider and you have 1/32 odds. The only way to get the odds to a realistic level is to make one parent a visual enchi clown. Don't you think RD would have wanted to show off his enchi clown before he bred it and produced the next level?
Think simpler:
Enchi clown: male enchi het clown x clown or het clown
enchi pastel clown: male enchi het clown x pastel clown or pastel het clown
desert pastel clown: male desert clown or desert het clown x female pastel clown or pastel het clown.
All the above males are available or can be produced and up to breeding size in a year. The females have all been around long enough to be breedable. They also have somewhat realistic odds, especially if you use a visual clown. RD would have good reason to keep the ingredients a secret.
You just dont get a super codom, recessive(basically another super), plus two other dom/codom genes into a snake without seeing the steps leading up to it.
Unless of course RD kept a male enchi clown a secret while he raised up a female enchi het clown to breeding size.