Diesel Van Heaters at Hi Altitude & Sub Zero Temperatures

I recently purchased & installed a diesel heater to our van as we intended to do more winter trips & stop over’s at bush camps. We gave it a few test runs at home & all went well & we were very happy with the results.
It’s the 2nd week in May & its time put it to the test expecting o/night temperatures of approximately -3 or -4. As we planned to stay 2 nights at Yarrangobilly Village Camp at an altitude of 1080 metres I rang the technical dept of the heater supplier re the diesel waxing up as Alpine Diesel was not yet available in our area & was advised to mix 1 part kero to 10 parts diesel to void waxing.
We arrived at the camp site early after lunch, a lovely tidy area by the Yarrangobilly River, the cleanest long drop loo’s I’ve seen (congratulations to the Local National Parks Dept). Once the sun dropped behind the hill so did the temperature, down to zero by 6 p.m. so cranked up the heater for a comfortable evening. We decided not to let it run all night but to turn it back on as required & attempted this after waking up cold about midnight. The heater refused to fire up & after many attempts we gave up & experienced a rather uncomfortable freezing & sleepless night. Next morning we had no hot or cold water as the pipes had frozen & when I ventured outside once the sun was up & shining (8.30 A.M.) the outside temperature was still only -6 degrees. We decided not to stay the 2nd night & set off at 10.30 hoping all would be ok with the ute fuel but you guessed it, midday before the diesel would pass through the filter.
I can except the ute not running due to low temperatures & lack of “alpine diesel” but am disappointed with the heater as we were lead to believe that the addition of the kero to the heater fuel tank would have solved that issue. The heater is manufactured in Europe & the manual states it is capable of running full time at altitudes of 1500 metres.
I am keen to hear from those that have used a diesel heater at high altitude & sub zero temperatures as to your experiences.
Cheers.