I never have buckled down and got a brooder plate. I only have a plated coop heater that stands up. I just plug it in and they sleep next to it. I do put bricks on it so it can't fall over. I would attach it to the wall if I could for sure!
I would put the brooder plate in there and let them decide what they do for a few nights. But yes I get stunk out and put mine outside around this time!