Yes, if she has Havanese type hair, clothes will definitely mat her, unless she's kept trimmed quite short. If she has a Pom type coat, she DEFINITELY doesn;'t need clothes. They were bred down from northern Spitz type dogs, and have a VERY warm under coat. Even if her coat is more Havanese, she will certainly not need clothes at indoor temperatures unless she is shaved down.
She has a shorter cut but not shaved right now (although her leg has a recently shaved spot from when she got fixed 3-4 weeks ago).
She wears a harness when she goes out on walks or car trips, and some of her harnesses are more vest/dress style.
The family yorkie has always loved wearing clothes. I could crochet a sweater and then put her in it and finish it while she was wearing it. ;-) but it was colder (near Philly area).
I wasn't sure about Bama and clothes. Although she was dressing up for Halloween. My husband thought she might start needing something to stay warm at night. It gets chilly at night, and we haven't gotten the heaters out yet.
Our place we live in is very old (80-90yr) and we have some wall heater in the main room we don't use, and nothing in the kitchen or bedroom but a portable floor heater (we use one in the living room too). But we will have to figure something else out for her safety.
Also, we know that Poms go through 'puppy uglies' when they transition from pup to adult fur. They can end up with patches with not much hair, and so we have tshirts on standby in case she does that instead of blowing coat.