I used to use a flip seat bracket from AAA with a dry box. It would work with a cooler as well. Or the DRE type flip seat. The DRE type would give you the best support without putting weight on your cooler that might cause damage.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb