Not a bad engine but it has a fuel injection cycle that follows the combustion cycle and some of the diesel ends up in the motor oil. You can get around this in part by much more frequent oil and filter changes. The LMM was replaced by the LML which added a 9th injector that puts fuel into the exhaust stream instead of the cylinders.
I have a LML diesel and would not recommend diesel for use with a camper. It is overkill and adds $9,000 to the price for a new truck and $5,000 to the price for a used truck. Diesel fuel costs more so any savings from more MPG is largely negated.
It is a pain to find diesel when traveling in remote areas. If you get a diesel truck be sure to get a larger fuel tank from Titan. Four out of five gas stations will not have diesel and I find that planning for fuel stops takes a great deal of time and overrides my considerations as to where to stop while traveling. I make more fuel stops to be sure I can make it on the next leg than would be the case if I was buying gasoline.
If I had it to do over I would go with a gas engine and 4.10 gears and be sure that my truck could take a Titan or Arrow oversize fuel tank.