This one falls into the "silly-looking things we do in the name of science" category:
This picture was taken when I was helping a fellow grad student out with her project. She was banding and taking a blood sample from the Laysan Albatross that had been sitting on that nest. My job was to stand still and cast enough of a shadow to keep direct sunlight from overheating the egg until the bird was back on the nest.
You make a perfectly adequate sun shade and, if you wish to pursue the option, may have a promising career in the specialty.
Your main competition may be the $12 totes folding umbrella and the 'comes with the $3 soda' quart-size Styrofoam cup. Moderate you remunerative expectations accordingly.
It would have been a much better picture with *two* eggs...