The rule does not specifically address field dressing the animal: the rule neither allows nor prohibits field dressing of road kill animals at the site.
However, you should be aware of local rules and laws associated with traffic stopping on roadways for any other purpose other than emergencies. For example, there are rules that would prohibit someone from stopping on an Interstate for any reason other than an emergency.
When salvaging wildlife you should be aware of your safety and the safety of others.
Also consider where you are and be mindful of leaving animal parts behind that can cause other wildlife to be victims of vehicle collision and also be conscientious of the sanitary issues involved. Would you want a gut pile left in your front yard?