Questions about double rex rat

[mues155]

Rex acts like an incomplete dominant trait and double rex a homozygous trait.
You need a rex X rex breeding to make a double rex.

This one looks to be a recessive trait hairless rat.

but shes not totally hairless. she has whiskers, peach fuzz and all that hair on her face and legs.
I'm pretty sure she would have a thymus then. which hairless rats lack.

she just doesnt seem to be the definition of a hairless rat.