My pony was chaser clipped at the end of November and has been out without a rug for the last 2 weeks. He lived out all winter anyway.
I am mean but he is a native pony and most of his clip has grown back and he gets itchy when moulting so it is nicer for him to roll about in mud and scratch himself without having a rug on. He also is a good doer so it is better for him to be leaner coming into the spring.
With the british weather constantly changing I don't think whatever you do you can guarantee your horse will never be to cold or to hot unless you live on site and can change rugs at very short notice as it can go from being cold in the morning to really warm in a few hours then rain then warm again etc.
I think occasionally being a bit cold is the lesser of the two evils if compared to being too fat or being too hot.
Mines a cob x TB and has been naked in the day for the last 2 weeks and had a rainsheet on at night if expected rain but naked overnight when not. They are all back in tonight as due to rain lots and has a cotton sheet on to keep her clean! She had a neck and belly clip in nov and it hasnt grown out yet!