I think the fact that her car was relatively clean, considering, and there was virtually no blood beyond Travis' bedroom, it speaks to her extreme degree of premeditation.
She came prepared with a plan including a plan to clean herself off and dispose of her clothing undetected. She would have been COVERED in blood from that crime. Think about just the dragging his bloody body part
She was in long dark pants and I think her Ninja description probably leaks her own "murder costume". Her hair , unless covered, was also likely covered in blood. She had to have cleaned up in that bathroom before exiting it.
I believe she came prepared with a bag to put everything in she planned on removing (no rope ever existed imo) and cleaned herself up in that shower, likely while Travis was in it (because she would have gotten bloody again moving him back in after cleaning off) which is one of the most disturbing ideas of her murderous rage. Rather her sociopathic evilness.
So I think she neatly packed up her bloody clothing with her weapons, was clean and showered in a new prepared outfit to walk out of that house in broad daylight and leave , maybe with a small amount of "blood on her hands" related to bloody items she had to interact with post clean up (of herself).
So I think those clothes are disposed somewhere between Travis' house and the Hoover dam. Just like she planned and carefully crafted. In her days and weeks of premeditation and planning.
All of which adds up to:
FIRST DEGREE MURDER