I really haven't had any problem.with comb frostbite. The only ones the frost got as some banty combs a few years ago.
They put their he's under their wings
It's their choice to roost out, I have a large hen house and several smaller buildings and pens they're encouraged tonroost in but they prefer the trees. I diidnt take a pic but I had 15 in the redbud tree the same day.
As per some poultry husbandry books written 100 years ago, chickens are far and away healthier and better off roosting in trees......right up until the moment a varmint or owl nabs them. If they can avoid that, they are golden.
I had one that got tired of getting beat up every night going to roost, so decided to take her chances in the barn. Coons got her the first night.