Hypo super mojaves and pastel ivories have both been done, you can see a visible difference in the color. I think someone made a pastel super mojave that was lighter than a regular super mojave, but I could be wrong.
I'm breeding butter het hypo x mojave het hypo this year:
http://i192.photobucket.com/albums/z...DSC_0980-1.jpg
If I got a leucistic out of this pairing I'm not sure that I'd be able to see a visible difference, but I would definitly breed it to a visual hypo or hypo combo to try to prove it out as a het or homozygous hypo.