I’ve owned both of the unicorn diesels (7.3ford and 5.9ram). My experience was like meeting your childhood hero’s later in life... it’s ok, but not what you thought. The premium you pay for a 25 year old diesel is pure insanity and as several above mentioned, the maintenance cycle is increased on diesel (as is the cost) especially if you’re paying others to do it. Both options are capable and will do the job of well maintained, but efficiency truly is t what people claim... it’s just not, sorry. You’re NOT getting 20 mpg on a camper truck with the aerodynamic properties of a cliff face. Stop perpetuating that lie! Please stop!
Get a gas variant and make life easy! They are long lived and quiet by comparison. Not prone to overheating, gas is easy to buy everywhere (not so for diesel) and something not mentioned is that diesel exhaust will permeate everything you own. The bedding, your clothes, your toilet paper, EVERYTHING! Feeling smelly and oily is only so much fun. It gets in your nose hair and never leaves lol.
(Can’t believe I’m saying this) because I prefer old and simple, but more modern gassers can deliver a smooth powerful output with zero drama these days. Fuel economy can be “reasonable” in several of the offerings from Ford and ram (special shout to Chevy 6.0/6.2) as well though I haven’t owned one.
at the end of the day, get a good truck that was maintained well and has the features you want. Suspension and power seats can always be added, but you can’t make an extra cab into a full 4 door,etc. All of the engines you see above will do the job so get the best one you can find with good maintenance history. You’ll have fun.