I think 6 months is a bit often!
I would guess if you do it once per year, every year, you wouldn’t need to sand, and therefore, you wouldn’t need to remove the bees from the box. Just paint or fabric apply in place. It isn’t toxic, and it doesn’t smell strong. It isn’t even particularly sticky, I don’t think it would trap bees like paint can.
The landing board is fairly easy. You wait until evening, then close the entrance. You can do that with an entrance reducer, tape, or my preference is a strip of #8 hardware cloth which you can buy from online bee supplies companies. Then either apply the oil that evening, or the next morning. When you remove the entrance block, stand to the side of the hive so you don’t get mobbed - even wearing protection and using a bit of smoke would be a good idea as bees tend to get more defensive at night.
The other option, as @Dee has said in another thread is not to treat at all. The beauty of Western Red Cedar is prolonged by Tung Oil, but it isn’t necessary to preserve the wood strength. It will remain rot and insect free for decades, even if you don’t treat it with anything. It is just that the color changes to a silver grey, instead of retaining the red tones.