I love making my character wear various types of cowboy hats, but they all hide her hairstyle thus spoiling the effect.
Is there a mod so that hairstyles remain unchanged when you wear hats? I'd really need that!

Unfortunately the hair is a single mesh that won't change to fit the hat. What this means is that you either have no hair style at all, or a hairstyle that pokes through the top of the hat.

In oblivion and fallout this was kind of addressed with an egm file which made the hat/hairstyle fit the head. However, at least in my game, there seem to be a lot of bugs where you get bald head poking through hair =/

The only way to have a hairstyle under a hat would be to make a new model of the hat with hair attached. I don't know of any modders atm that have done this but some might in the future?

Ah, now I understand the reason why a character's hairstyle disappears or changes when wearing an hat!
So there's no way to wear the hat over the hair mesh I suppose (I don't know much of this technical stuff).

I still hope there'll be a workaround for that eventually. Thanks!