I have come into this thread very late and have two things to contribute.
1. If you want good coffee on a gas burner the best way we have found is an Italian Bialetti which does fantastic coffee. We have a 6 cup and have used it when travelling. At home we have a nice Breville dual boiler coffee machine which makes great coffee, but in the van we have always used the Bialetti and it makes very good coffee, better than most coffee shops (if you use quality freshly ground coffee).
The Bialetti 6 cups are 6 short blacks so for two of us we have two mugs of coffee out of one pot. If you want more coffees I suggest the 12 cup Bialetti. It works nicely on a gas burner, if you want a flat white just microwave the milk and add the short blacks from the Bialetti. If away from 240V we just carefully heat the milk on another gas burner, while being very careful not to boil the milk.
http://www.bialetti.com/www.bialett...-1_7_22.html?zenid=87p151ki41jkso9esr3mccd9a5
They often can be picked up in most good coffee roasters and larger retail stores or online.
2. With inverters there are two types full sine wave and modified sine wave, full sine wave are much more expensive, but are more versatile especially for running computers, etc. Waeco and Xantrex make good pure sine wave inverters, Waeco is about half the price of the Xantrex and the comparison of the two is a bit like Holden vs Mercedes. There are some good Chinese pure sine wave inverters, a lot cheaper, but a bit of a lottery.
http://www.xantrex.com/power-products/power-inverters/prosine.aspx
http://caravansplus.com.au/catalog/product_info.php?products_id=13869
Both inverters are sometimes cheaper on eBay, but make sure they are 12V to 240V (not 110V) models.
Good coffee and good leaf tea (not tea bags or instant coffee) are always worth the trouble, life is too short to drink rubbish.
A bit like wine, all alcohol is poison so only drink good quality poison that tastes great.
Regards
Terry