Many have used strap hinges when the break is at the frame which is the most common place for the breaks to occur. They have attached one side of the hinge to the frame and the other to the plastic support by drilling matching holes and bolt it together. It works great and is a lasting fix. Mine is situated so this won't work because of its proximity to other supporting structures. My luck. The support strap is 3.5 inches wide and can be purchased on Lipperts web site.
Retired Fire Dept Battalion Chief
2012 F150 FX4/ Max tow and Ecoboost
2016 Ever-Lite 232RBS