Ya- the all-thread bolts are kinda silly-trying to figure it out it appears at one time T/L did supply shouldered.
Unknown why they changed and added an extra inch to boot.
I ended swapping, to get length in SST at local hardware was 3" lg with 2 1/8" shoulder, better for going thru step bars and the nylon spacers.
Also cut them to 2 11/16" to minimize stick out. Ran from inside out with nylock.
Noted your pins are between treads- my instruction said to mount at step 3, which doesnt work flush mounting. Mounted between #3&4.
One of the many small items that lead me to believe Torklift really didnt make allowances for flush mounted...
As to the flex, mine the entire bracket flexed, lower half of the side plates sets 1/4" away from bumper.
I added 2 corner pieces to support. Wouldn't do anything for the 1/4" pins against the rubber stops but did overall stiffen a lot.
My concern was, cutting top corners, flex would cause to crack.
Skate board wheel to replace the rubber?