Hi Erland
I was over in the Kullu valley in northern india a couple of years ago where I saw bananas (presumably sikkimensis) growing on the valley sides down near the river. I have been looking at the weather stats for Darjeeling and Gangtok to get an idea of the climate where these species are native.
I was also looking at this study
http://www.ipgri.cgiar.org/Publicati...ns/52/ch34.htm
which suggests that one of the keys is the amplitude of the day/night variation. I'll post a couple of photos of my setup shortly. I've wrapped the tank in bubblewrap this morning and am now getting 27/28C. I just need to check that the night temp is OK.
I'll let you know
Kev