You can make a lid entirely out of insulation board glued together with spray foam. Just build it tall enough to clear. It doesn't need to be attached, some soft foam sealer where the edges meet would be enough.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk