Red and Blue will offset the natural colors of the morph...As one may think that it will make the snake stand out...When you actually want something that could compliment the snake.
I would go, Black (mainly with the lighter based morphs) and White (for the darker based morphs)
If you choose colors... I would experiment more with earth-tone colors instead. Navy Blues, Burgundy, Light Browns, Gray, Earth-based yellows like Yellow Ochre, and so forth.
These colors won't blend in with the snake as well as certain colors can compliment it, (Ochre Yellow could compliment something like a Cinny.)