[urq] Anyone ever try to add metal to the sills or roof to stiffen the urq chassis?

[steven j]

I might have repairs done to the sills and it occurred to me if a little extra metal was added maybe the chassis stiffness gained might be worth it.   These cars are pretty flimsy by today's standards,  if you jack up a corner the doors don't shut well.    Maybe flexibility contributes to windshield cracking?
I'm not interested in adding a cage.