.......ALL of the 4cyl turbo diesel duel cabs have clutch problems and are thirsty with an auto.
D40 (YD25 engine) navaras have problems with timing chains and guides, oil pump failures and turbo failures.
Ask my sister, almost $5000 in trade price parts to fix the turbo, guides and oil pump. They were just lucky her husband spotted the oil pressure light as soon as it came on and he shut the engine down.
I know of 5 sub 90 000km D40's with the same oil pump failure and that's just in Townsville in the last 12 months. There is going to be 6th on soon. I had the lower sump off one to repair a stripped thread and found the tell tale oil pump debris in the bottom. (the guy traded it on a new car)
Avoid any nissan with a ZD30 engine.
Hilux's have injector problems.
Tritons have issues with EGR depositing carbon through the intake, same for BT-50/Ranger plus on the last two the T-MAP (combined intake temp and manifold pressure sensor) is a few cm away from the EGR port and it blocks up the sensor in less then 50 000km.
BT-50/Ranger also has problems with cracking EGR coolers allowing coolant to enter the intake.
It's been mentioned already about Prado trans temp issues.
Patrols and Cruisers just keep going and don't suffer any of these issues so long as you stay away from anything with a ZD30 engine it or the V8 diesel cruiser as it has the same injector issues as the Hilux.
Before anyone says anything about Patrol 5th gear splins, they are a cheap fix compared all of the above. Plus you can get upgraded parts to stop it reoccurring. With the other problems mentioned, you can only replace broken substandard parts with new substandard parts.
ALL dual cabs in this case sounds like D40 Nissans
D-max has been fine so far for me - no sign of clutch issues after 45k, with over half of that towing as below. That said, I am mindful of how I treat the clutch and, as you state, there are some real issues out there with puss clutches on Dual cabs. I looked into this a fair bit before settling on Isuzu 2 years ago - there was no cases in the interweb that I could see in this regard. Also, the now older model dmax I have was de-tuned in auto form in terms of Torque output. If I was to get the new model now, the new auto box and matching pwr/torque to the manual would be a no brainer.
Back on topic...
Spending $25k instead of say $15k on a camper does not get you $10,000 worth of better camper in my opinion, e.g $15k will get you a good trackabout that is only a few years old.
Re tow rig - yes you could get away with under 20k for a 10-12 yr old rig with low k's IF you can find one, but if, as in this case, the money is there, then get as new as you can.
Nutto