Major maintenance investments around 250K miles?

This. 2013 v6 trucks are a good year. But at that mileage, spend the 100-200 bucks to get it on a lift and have it inspected (as well as you personally being able to take a look at it on the lift). Rust will be the biggest thing, look out for that like a hawk.

Everything else, driveline wise if documented done at proper intervals for that price wouldnt be a bad buy... not great but in this day and age of pricing of things is quite good.

 

Pay a mechanic to look at it

My 2015 has 151,000 and at this rate I'll probably hit 200k in less than 2 years. The only warning light I've ever seen is the tpms when I air down. I have zero worries about hitting 200k

If it's clean inside, and the mechanical checks out underneath go for it