Or at least a plan for it. Given the flex, here’s the plan:
Support door end of 40′ with a 2.5″ steel tube (.25″ walls) centered under the end.
Support back end of 40′ with 2 x 1.75″ tubes (1/8″ walls) centered under the corner castings.
Cement at the base of all 3, to same height as 20′ containers’ footers. I’ll post a bit on why all this is more than adequate to prevent big metal legos falling on my head tomorrow.