It'll dip down cool at night but the road will still be nice and warm. The cows will lie down in the road and you generally won't notice them until you're about to hit them.
Over the years I've read articles about at least a half-dozen motorcyclists that dug in that way...
Incidentally, when you're in open range territory, that law is "fence out" not "fence in."
Maybe the highway department ought to be responsible to fence out those pesky animals (that we eat) in order to protect those fun-lovin' motorbike riders.
Isn't it up to the government to protect us all from ALL possible hazards? That's why we wear lapbelts and helmets, right?