I have seen these used. One young lady has significant sensory issues and used it to help reduce the challenges that this entails. However, the issue arises around matching of skin tone. The contrast between the "suit" and the skin on hands and face make it quite obvious; they are often shiny as well, which makes it very noticeable on the ice.
If your DD is cold, there are simpler solutions:
a) use heavy weight tights, and double them up.
b) wear high collared and long-sleeved dresses, and put thermal layers underneath. Thin "skiing" type underwear doesn't show up, and, usually, little girl's dresses don't fit skin tight, so you can hide a layer under nicely.
c) there are polartec dresses out there that look like velvet. We have one ... very cozy for cold rinks.
Judges really hate seeing shivering little girls on the ice. They quite like seeing them looking comfortable and covered up, so don't worry about making sure they're warm.