Hi Wil,
While I have a 200 TTD now, my previous vehicle was a 3.0TD GU and before that, an 80 series 1HZ.
If I had to choose between the GU and a 1HZ powered 80, there is no way it would be the 80 if towing a camper trailer. Many have knocked the 3.0TD for its engine reputation issues but at the end of the day, I have known personally some 20 odd 3.0TD owners (mostly from 4WD club) and not one has had a piston holing engine issue - certainly there have been some issues amongst them, but none had the "grenade" problem. Yes, I know many others have, but what is the actual percentage that do? Point being, while the 3.0TD has had more than its fair share of problems, so do all other makes too.
But the 3.0TD is so tainted now that most wouldn't buy one. The 100 series 4.2TD is great, alog with its price tag, so realitically its out of the question. But have you considered a 4.8 5sp GU? Yes, it drinks fuel like no tomorrow (well, only about 25% worse in reality) but it is arguably THE most reliable motor around - including any Toyota motor you may want to compare it to. The 5sp auto is a pearler and being a GU, there is no shortage of aftermarket goodies for it.
Anyway, if I was in your positon, I would be looking at just how many kms I do and what the extra $/year it would cost to own a 4.8 GU. There is no lack of power and it has the reliability and off-road ability.
Well. thats my 2 cents worth
Cheers