So are these physical, skinsuit disguises, or more like glamour/illusion? Gammaton's current form is a little grubby, and probably couldn't wear a skinsuit. Gammaton is also an illusionist, so probably wouldn't need one, unless we are worried about enemies with truesight and/or dispel magic. For a more optimal disguise, Gammaton could accelerate her metamorphosis until she is reborn as an egg, and gets implanted into the neck of a live host. She'll merge with their nervous system and acquire their memories, allowing her to become the perfect spy.