Not to downplay your issues, and in your shoes, I'd want to burn that turd too.
I can also say that having had probably 40 or so personal and company trucks in the last 25ish years, I've had 1 or more trucks from each of the big 3 that had a problem or problems that shouldn't have happened.
Some of the issues could be related to dealer incompetence (front end namely. I had a tire eater that the alignment shop couldn't fix and I aligned it with a stick and strings and voila, no more issues....)
Couple things point you squarely at a diesel, if not this one then another one.
1. You're planning on a big 5ver that will s uck to tow with a gasser, any gasser. Safe? Sure. Not as safe as with an exhaust brake in the hills but the chassis will pull it. Just be ready for milquetoast at best and crappy at worst pulling power for that size trailer.
2. You "commute" 4 hours a day with the truck. What's that 150-200miles? Gasser will net you 13mpg average on good days if you're not in a hurry. Diesel 17mpg ish. Or about 400 extra gallons of fuel per school year. Not to mention the 30k miles (estimated) a year of wear n tear on the engine. Yes new gassers are good for 200k + miles all day long. Diesels still win for longevity. The rest of the truck is a wash, save for maybe the trans. In general the heavier duty the vehicle and the lesser the duty cycle it sees, the longer it lasts.
I'll leave the rest of the cost/residual value discussion alone.
But to say that all of the big 3 diesels are generally regarded as quite reliable is an accurate statement and I think you just got one with a few issues, none of which sounds like the engine.
