New 2004 Tundra owners nervous about frame

My dad and I just bought a 2004 Tundra SR5 Access Cab in a private party sale. We did well based on Blue Book value and its state inspection is good for another 14 months, but I'm nervous about the frame.
There was a small hole in the frame toward the back of the front driver's side wheel well a little bigger than a quarter, so we had the seller get a new inspection. Aside from some surface rust, the rest of the frame looked fine. The hole is a bit bigger now, about half a credit card size, as a result of them poking at it and banging on the frame during the inspection. I plan on trying to get the hole patched and then cleaning up and repairing the rest of the frame.
This is going to be a utility truck driven less than 5,000 miles per year. I'm hoping a frame patch and surface rust repair keeps it on the road past 200,000 (it's a little under 166,000 now).

 

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