Wondered about this myself, I'd like to use heated water as well....I don't think that heating it overnight will work particularly well though, without constant heat it would soon go cold. I've seen the 'official' gas bottle heater equipment from Omnipole...looks bulky. I'd like something for my omnitrolly too...but not that....some sort of kettle element that plugs into the cigarette lighter would be better, but I expect it would want to draw too many amps. Likewise, I'd like to get hold of a battery charger for the trolley that connects in the same way, rather than having to plug it into the mains. Don't know if the technology is out there yet.......