lining a head

So, recently trying to up my professionalism and quality of the stuff I make (still very much in the process of it, learning new things that make my stuff better all the time, and very far from where I want to be yet!) and one of the things I'm uncertain about is lining heads.

I typically build my heads onto balaclava, then sew the balaclava to the neck. Would you makers/buyers consider this a lined head, or would additional lining need to be added for it to qualify as a lined head? One of the reasons I'm concerned about adding an additional layer of fabric is heat, but if it's something people think is a good idea, I'm definitely all ears.

If an additional layer of lining is needed, any info on this would be great. I'm not sure what fabric is typically used for lining. Would it be more lycra like material? Like the balaclava? And when during the process would one line the head? I'm currently working on a head, and if I chose to line it now, (it's like 95% done) I wouldn't even know how to go about it, and make sure the head still fits and everything. Any kind of WIP or info on how to go about lining a head would be super appreciated (if people think that the balaclava is not enough).

Thanks!