"7/16-14UNC x 3.75
bolts available at 4" or 4.5" $3.80 each
https://www.hi-tensilebolt.com.au/
I am thinking to simply place some 1/8" sheet alongside the frame rail, and use the slightly longer bolt
my presumption being this will reduce the concentration of stress upon the frame rail around the bolt head, and distribute it more evenly
reduce risk of frame rail cracking is my goal here
anyone disagree?