I have had my twins in my 46 2-ton with lap belts. It is not often, but on occasion. They just turned 7... Yes, it may not meet the law, but there are lap belts installed and it is just my opinion that you just can't be that careful all the time.
Every once in a while you have to break the rules. Plenty of people and kids rode in these trucks when they were new. And yes, plenty of people and kids were hurt in them, but that could easily be said about modern vehicles as well....
But I also take my kids on the road in a 1921 Model T and they will be riding in a 1915 rumble seat speedster this spring!
My .02$ worth!