Ferret
Had the diesel hot water heater on my recently sold KK. It worked brilliantly, very economical on diesel, took about 7 mins to heat the water and could draw water from any water source. The only issue I had with it was that it would trip the circuit breaker if I had the fridge running at the same time, possibly too much load? Once I became aware of this, wasn't an issue.
Can't recommend it highly enough and would love to get the KK portable diesel HW unit for my next camper, but at $3K, it's a little to steep for me.
Cheers
Baz