The problem with midsize trucks is that they aren't actually much smaller than a full size truck now, except that for some inexplicable reason the box is about an inch too narrow to put a sheet of plywood in the back. Also these midsize trucks are nearly as expensive as the full size and, like you say, they don't get significantly better fuel efficiency than the full size truck. Given these facts it's no wonder North Americans prefer the full-size trucks.
As for the Lightning, it is a reasonably good fit for the farm. I burn tons of gas putting around checking on irrigation. Electric would do it except for a couple of issues: curb weight and overall price. The weight alone gives me pause as I drive in soft fields and don't want to get stuck all the time, or leave horrible ruts.
Ironically the people that actually work for a living and need trucks are such a small market compared to those who just want to drive around luxury trucks as as status symbol. So we end up having to buy trucks that really have way more bells and whistles than we need (carpet for one). Trucks that are meant for trades people do exist and they do sell pretty well. They also tend to be just one color, white. But I'm glad I still have some options.