To "paint" over the logs with a light semi-transparent stain or "whitewash" to lighten the logs, but still let the wood grain show through? I don't know if it would work, but might be worth a try to lighten up the interior. Try a small hidden area first. The only other solution I can think of is to add as many lights with as high a wattage as you can to "lighten" the interior. Good Luck! Dodgeman