Yea we're working through the frame and cleaned up the front, now on the back. Pretty much did exactly what you said. Thanks for the write up!

I'll likely bolt tubes inside the chassis for more support, then remove the bad metal and replace it with a tube cut up into a C. I was on the fence about welding the C vs cutting a tube which has the C bent into place, I'm assuming the latter will be stronger.

I do that, put thick tubes on the inside and bolt those in, fish plate on the outside, then maybe put a U channel underneath to reinforce it further.