Personally I do not worry too much about the noise.
A few feet away from the vehicle on most campsites and it's inaudible with all the other background noise going on.
I've just come back from a couple of weeks in France and Belgium, mostly on Aires where vehicles are quite close together, and no complaints. After all, if it's cold enough to need it running at night then it's cold enough for most other happy campers to sleep with their windows closed and if you can hardly hear it in your own closed van then you are not going to hear it in a closed van parked a few metres away.
Inside noise, yes there is the ticking, that's about all, and the point is soon reached where the senses become so accustomed to it that it does not even register.
One of the great pleasures to me about the Cali is being camped in foul, cold weather and being wrapped up all snug and warm inside, a lovely cosy feeling and what woollie slipper-socks were made for.
As Pete has pointed out ... FIRE ANGEL... for £20 an indispensable companion.