While regulatory capture is a huge problem, in this case, auto manufacturers definitely didn't write this. They would like nothing more than to see it go away, or at least rolled back to where it was a couple decades ago. Overall that would be bad for fuel efficiency standards, but it would allow for small pickups again.

In my completely amateur opinion, a solution would be a cutoff on the wheelbase where a vehicle was no longer a car/light truck, but a new catagory with different higher standards. Or maybe a carve out for vehicles with a bed that allowed a little wiggle room for smaller vehicles. I don't like the idea of allowing less fuel efficiency, but if the choice is between a small truck that misses the fuel requirements of a similarly sized car by a few MPG or a behemoth with half the MPG, I'll come down on the side of a carve out for little trucks.