Is it okay to eat five guys burgers with a moderate peanut allergy?

Mgt. I agree that asking the restaurant is important to determine the ingredients. Very often the cooking area and dining area can be a source of cross contamination. For example a shared utensil, salad dressing with peanuts. I would suggest asking your PCP about an Epi Pen.
Peanut allergy. Inquire with the restaurant if there are any peanut traces in their cooking and/or read the food label if packaged.