No USB charging - that would be taking things way too far

To be honest the 3 lights in the kitchen/common area are pushing it somewhat, though useful for conserving your headlamp batteries, and do give the place a nice ambiance at night.
The gas versus electric heating is an interesting question. Probably cheaper in the long run to fly in cylinders a couple of times a year versus install, maintain and replace enough panels and batteries to match the heat output. I can't imagine the batteries would be long lived out there in the cold of winter, and of course the panels would be covered in snow a fair bit too, reducing efficiency.
Can't complain about the gas heater though. It doesn't belt out heat obviously like a your average domestic heater, but it takes the chill out of the main area very well and looks pretty inviting too, especially when it's -7 degrees C outside.