I just had Safe-T-Caps welded in along several spots in my 3rd gen frame. As mentioned above, no collision repair shop or body shop wanted to touch it for liability reasons. One even told me it was illegal to repair frames with patches.
I went to the Auto Rust website and looked up certified installers in my state. There were two. I called them both and went with the shop I was more comfortable with.
I paid about 40% more for the parts then I would have by ordering them myself online, but they told me they were only allowed to charge up to a specific hourly labor rate by Safe-T-Cap that was lower than their normal shop labor rate, so it was a wash compared to me buying parts and just paying labor.
I pretty much had the entire driver's side done for good measure and two spots on the passenger side, including the inner spot where the trailing arm meets the frame by the exhaust pipe.
I paid just north of $2k for everything but consider it money well spent to have a solid frame to build on. I certainly do not have the tools or skill set to do that type of thing myself.