G'day down there! Been a while since I've tipped one back at the St. Kilda yacht club myself, but I have to say that if you're winging about the winters in Melbourne, you're a bit soft mate.
Now if you're interested in keeping the lady happy, may I suggest a wood stove. Almost instant heat and HEAPS of it. I had a cole stove (no longer made but identical to the dickinson solid fuel stove) which was not airtight so it was fiddly but I could have my 30ft wooden boat up to 40c in as many minutes if I wanted. It also had a grate to watch the fire which was tres' romantic.
I don't have direct experience with these stoves but they look great, they come in small, smaller and really smallest and are cheap. Try using the compressed 2hr wax firelogs they sell at supermarkets. Duraflame is one brand. I would hack off a double fist sized piece and put it in the stove. They burn consistently, and not as hot (but plenty hot enough) as wood. They last longer than wood too. Once you have a nice glowing source of heat you can ventilate the boat better and the stuffness goes away.
Check this out: