Ouchh... sorry for you...
I've just removed the wheel to wheel aluminium steps, they are just bolted on cab and bed and to the fenders with mud flaps... It's just a good thing to add rust because the cab and the bed don't move together because of the flexibility of the frame and that peels the paint off near the bolts...
Others are bolted on the cab to frame supports... I've begun to make them myself because I don't want to put so much money on steps, and I didn't find anything on the net that suits my needs and budget...
You should perhaps have something directly bolted to the frame with 3 or 4 supports, it will be very heavy, and in a side impact hope that will not damage the frame, but it should be very solid in little impacts and off-road (mine will be just the cab lenght... )
It might be high-end products, so perhaps you should make a draw and go to a welding shop ?