I have over 500k kms/310k miles and just did a 1000kms trip this past weekend. Trailer is only 8k lbs. Truck is my daily driver.
Wouldn't hesitate to drive it 5x that for a trip. I'm the guy that does all the work on it so I have only one person to blame for any issues, but I'm also the guy that got it this far.
Depends on your comfort zone. It's the little things that get me now, a leaky PS hose, sensors but I'm not worried about the engine or tranny grenading. Truck has never stranded me.
Regular engine and transmission maintenance, brakes, suspension, steering and electrical service are all part of owning any vehicle including a new one. They are maintenance items and all wear out long before engines and transmissions do.