While a white gas/gasoline powered stove seems ideal -
In many ways it is. I have one, and use it most of the time. In Australia, Blakerwry, we have very high fire risk (probable the worst of any country in the world, although fires get pretty bad in several other places) and on high-risk days have Total Fire Bans - i.e., you cannot light a fire or a gas stove, harvest wheat, or even use an angle grinder unless you are securely indoors. You can't even use a BBQ in your own back yard.
These bans are not just essential for fire safety, they are backed by some serious penalties - I forget exactly what but I think it's a $10,000 fine plus 6 months in jail. Something of that order in any case. This is not unreasonable when you recall that a single fire can burn out hundreds of square kilometers, sometimes thousands, cost hundreds of millions of dollars in damage and firefighting costs (hired a big helicopter lately? that's serious money), and kill people. (Three people died in a bushfire in Western Australia just two weeks ago, for example. It's not uncommon.)
The other day, by way of example, I was in South Australia. Almost all of the state had a Total Fire Ban, except a small region in the east where it was judged that the weather was a little milder, and where, it so happened, I was planning to pass through anyway on my way back to Victoria. That meant that I could make camp on the South Australian side of the border, have a cup of tea, and fill the thermos - all before midnight, because at midnight a state-wide ban came into effect because of even hotter weather. (It was 45 degrees that day - for the backward ones that's 113 Farenheight. The next day was forecast cooler at around 40 degrees, but very strong winds, hence the extension of the ban to all parts of the state.)
Over the border in Victoria there was also a fire ban - and rightly so, it was wild weather and if a fire started you wouldn't get it out this side of February.
So any form of fire is out, alas. It has to be electric, solar, or some form of internal combustion.
You can get electric 12V imersion heaters but they draw a lot of power, take forever, and are horribly unreliable el-crappola made-in-China things. My last one made precisely one and a half cups of tea before it crapped out. The one before lasted about three. Junk.
You can get electric cups that run off your cigar lighter, but they too are el-crapola. The one I bought, thanks to the bloody lawyers, won't heat anything up to boiling no matter how long you leave it running, but cuts out at a dreadful and undrinkable luke-warm temperature wich would not really do for coffee and isnt even close enough to the temperature you need for making tea.
You can of course tow a caravan and use the gas stove in it, but I'm damned if I'm going to tow a whole bloody caravan just to boil water. I sleep outdoors and travel light.
I have an inverter but it's not big enough to run a kettle from, it's just for the laptop and cameras.
You can get 12V kettles, but I doubt the ability of the electrical system to stand up to the draw. Still, it's a possibility.
I've toyed with the idea of using the exhaust manifold, but don't really know where to go with that idea.
Solar is very slow and sensitive to wind, and probably not practical for someone who moves around as much as I do. In any case, the main times I want hot water are early motrning before sunrise and late in the evening after the lihght has gone.
Maybe the most practical option is an internal combustion generator/inverter plus a kettle. Unfortunately, kettles are high-power devices and you would need a pretty big generator to run one - yet more weight and bulk to squeze into a fairly small car - and I don't want a bigger car, I burn enough juice running this one - 11,000 kilometres in the last 30 days.
I dunno ... it's a puzzle
Then Santy had a mechanical problem and was semi-trapped in the chimney. It was hysterical. 
