Finally got around to cleaning up the frame and giving it a coat of Corroseal and Fluid Film but found one spot that needs some attention, no issues anywhere else. Odd only one side but there was a bunch of mud caked up inside. There is a 1/2 drain hole in this spot and seems to have rusted around it. Cleaned out inside, sides and top are good.

I can weld half decent so no issues patching but what is the best way? Was planning on using 1/8 or 3/16 plate. Should I cut out and weld in a flush patch, patch overtop?

Thanks