[ChuckMcM]

I really wish that regular trailers would develop some sort of standard linkage system rather than the SAE ball. I want to back up to my trailer and have it hitch a load equalizing connection without having raise/lower and get grease all over my hands and pants.

[Animats]

There is. Tractors for semitrailers have a fifth wheel, of course. That's the 90mm size. There's a smaller 50mm size used for RV trailers. The hitch for that bolts into the truck bed.

[ChuckMcM]

Yes, but no. The thing is I don't want to give up the bed of my truck in order to hitch. I use the truck as a truck when it isn't attached to the trailer.

So something more in line with the rail car system is in order.