For long term lighting during wintertime I will be using a Bullfinch 1616 Handilight Lantern. It will give me approx 250 hrs continuous use at an equivalent 100W incandescent light output (150W @96gms/hr) i.e. around 1250-1500 Lumen when using a standard 15Kg LPG bottle. So if in use for 6 hrs per day would give me around 6 weeks use operationally on a single LPG bottle.

http://www.gasproducts.co.uk/acatalog/Bullfinch_1616_Handilight_Gas_Lantern.html

It also has the other benefit of providing some supplementary heat output as well during long 16 hr winter nights. During summertime it doesn't really get dark (sunset around 11pm and rises around 5am) and a solar PV battery system/LED lighting will easily cope with any outages.