I think I'll chime in with some cents of thoughts.
I like what tantaka48 said above. There are certainly some advantages to both routes. Personally, I would never get a newer truck than a 97 7.3 (at least right now). Here is the reasons why. As most have already said before, it's relatively simple, wide range of parts availability, updated/upgraded parts for common known issues, and cost. Sometimes I actually wish I had a IDI-T instead. Now granted, I searched for 2 years for my truck. Yes, 2 years. But I found a primo truck in excellent shape right at KBB price. You can say it was a gift from above. Since I've owned it I have done significant work. Check out my build thread if you wish. It still comes in at quite a bit under cost for a new factory truck today, with lots of things that a factory truck doesn't have. Plus, I can work on it easier. From my experience, the whole 'computer' talk is still a valid one. If a computer fails, though they are becoming more and more reliable, your stuck. Usually, if it is some sort of mechanical failure, you can still limp to a shop somewhere close by. Because the older trucks have been around a while, they have a huge market with tons of parts and 'toys' available to allow you to build it as you wish basically. Many like the last generation of 7.3's however, I actually prefer leaf springs up front due to a future plan of making the front suspension loose, but backed by air bags, for utmost in flexibility. Point is, newer trucks don't have the aftermarket backing them as much yet as they haven't been around as long, and many designs don't allow for such modifications. THey also, as you know, have a good track record, being strong runners after 20 years.... Yes, they don't have all the nice comfortable fancy interiors, but sometimes less is more. That being said, you would be hard pressed to put a heavy camper in one of these older trucks, or for any 1-ton series of trucks in general. Many people say they will haul a 3K plus camper, and possibly off the road, but that leaves zero room for a safety margin, and more than likely they are over the weighted capacities for tires, truck, and axle. Then again, no matter what truck you have, if your hauling a 3K camper then your probably sticking to places with roads anyway and need a dual rear.
Now, my dad recently bought a new Ram 3500 (single rear) along with a 13K or so travel trailer (OutdoorMfg.). I have driven it a fair amount, and I will be honest that it is a super awesome truck! It's quiet, it handles really nice, has some pretty cool comfort features, and is all around pretty awesome. It also hauls significantly better than my truck, but I would imagine it should since it has 20 years of updated research and development! But, he has that stupid DEF fluid which is terrible, does nothing good for the environment like it supposedly does, and is a huge annoyance of having to fill up. He, also, can only haul a little over 3K in the bed, and tow only 2K more than me (legally) and stay within a fair safety margin. So honestly, in my opinion, one would need a Class 5 or 6 truck if they safely and seriously want to haul a super heavy camper and tow, within reason. Being over the sticker weight is one thing, since most axles support quite a bit more than advertised. But being overweight on the tires, that's something entirely different in my mind. But, at about 70K for his truck, he would be looking to spend over 100K total to have the same goodies in his truck that I have in mine where I'm already at half the cost of his truck (or abouts), with a bunch of cool stuff.
That being said, the one huge advantage these newer trucks have over the older ones is brakes. Now considering safety, and even just drivability, this is hands down this is (or should be) the biggest single topic of discussion between new and old trucks, in my opinion (aside from cost). I will say the one major gripe I have about my truck, that I really cannot fix without major modification, is the brakes. I don't like having crappy brakes, and they are pretty crappy. Not terrible, but bad enough to make for potential issues in an emergency situation, or being super careful on a steep downgrade whether on or off the highway.
So all that said, one thing to keep in mind, from my perspective anyway, is I would in no way ever get a Ford newer than the 10th gen truck series. Having been a master tech for them for some years, they always push the envelope with technology and development and spend resources on 'cool' things, which is all well and good, except it makes for pretty big differences from year to year and raises concerns over reliability. Whereas the Ram series, though still having changes, is much more simple, and uses the same basic engine year after year. So given the potential of winning the lottery in the future, I would only go with a Ram. Although, if I could even ever afford it, and if money was not a factor, I would much rather just go with a custom build from Legacy.
So I think what it really comes down to, is how much money you have, and how much you want to modify the truck, and what would you truly use the truck for majority of the time. If you want to just use what comes factory, and have the cash for a new truck, go for it. You'll be happy. But if you want to tinker, and modify it to suite your specific needs and desires, a 10th gen truck or older (Ford) will be best. Either way, I think a super heavy camper is not outside reason of any Class 3 series of trucks.