He's experimented with numbers of candles, inverted flower pots over them. Not much heat but it sounds like he took the edge off the UK winter when he was intermittently onboard 21 or so foot boats. We use candles on our boat for ambient light but I suppose they put out a bit of heat too.

Even candles give off moisture but not as much as the Origo alchohol. Just the nature of any combustion that is unvented, plus the risks of CO are higher. In your climate and situation, I'd try the Origo heater.