We recently installed 2 large gas lights at my camp. They ran right about $100 each, but they throw out a TON of light and some pretty good heat too. We're gonna get a third one and between the 3, they'll light up the whole first floor. Saves a ton of propane ( rather than run the generator for hours ) and we get heat out of them to boot. We heat with a big woodstove mainly, but we have electric baseboard heat for when we first arrive and the cabin is cold. Once the woodstove gets cooking, we turn off the baseboard heat. Last year when it wasn't too cold ( 40 to 50 deg. outside ), the 2 gas lights gave us all the light and heat we needed. They took the chill out of the cabin's first floor - and our cabin is fairly good sized. We'll have that 3rd one installed by this fall. Best $$$ we've spent recently. :)
I see from your pix you have gas lights in there already. Easy to get a couple big ones and add those in.