In my state, any rust hole in a frame is instant inspection fail. Now That can be fixed. As I am fixing an arch hole now in my passenger arch.

My method is internal plating of boxed frames. You have to be careful when how much steel is rotted away though. This is why everyone recommends the external plating from safety cap which is a good method except for 2 things. Cleaning the inside of the frame out and coating it with rust prevention liquid of your choice. If folks would clean out the rust and scale out of their frames then coat and paint or coat it with a rust prevention liquid this would slow down the internal rotting of the metal and make it last longer.

My one frame I did was experimental and thrown together in 2015. Because I did nothing but just plate it in 2015, I have to go back in areas to fix it again. Along with fixing other areas that were fine in 2015. So I am done with external plating unless there is no other way to fix it and is some cases there inst.

You mostly have 5 to 7 years left if your rig is in the rust belt if you do nothing to slow down and stop the rust with external plating. As the steel will continue to rot away inside and will be up to your weld lines by then.

Well that is what my experiment showed here in western pa on my Tetanus 1.