[mba] Mash tun Lid Seal

Has anyone tried further sealing their (rectangular) cooler mash tun lid(s) with silicone or another food safe material? Been doing some research on it because the lid of my Coleman Xtreme cooler has plenty of leaks due to it not being flush with the base of the cooler. Particularly in the middle where the latch is and at 2 points on each side above the handles. Was thinking about perhaps wrapping something around the lip of the cooler lid to create a better seal, or perhaps just taking a rectangle of some sort of insulation and attaching that to the bottom of the lid to create the same sealing effect and add some additional top side heat retention. Just not certain what route would be best, nor exactly what materials to use. A flexible Styrofoam like material would be perfect for the 2nd idea. Just curious about others experiences and thoughts. Cheers! Beckel