So I know that sometimes sweaters aren’t the best option because they prevent the chickens feathers from fluffing up to lock heat in. However because he is a frizzle, I know his feathers probably don’t fluff the same as regular feathers and don’t lock much heat in anyways, so maybe you could try it and see how it goes.
I agree with you, though, a wet chicken can be dangerous, especially in anything below like 70 degrees. Do keep an eye on him. My pea brained chickens tend to not know that their coop is their best shelter from rain sometimes, either. When it rains you may just have to heard him somewhere dry and sheltered yourself. I end up having to do that when we get downpours.
So you have the ability to run a little heating pad out to his crate, is it an option to get a little heater out for him in an enclosed area? Oil filled radiant heaters work well as they have tip over shut offs usually and settings for a wide range of temps. That way if he does get wet, at least he can dry off somewhere warm.
Another idea, maybe you could enclose the porch somehow to make him a little area he really can’t leave unless you open the door to when it is nice?
