Travis could have done that, after, I assume, he asked her to leave.
MOO
I have always thought that Travis stripped his own bed and put his sheets in the washer, then dryer.
The furniture (iIrc) was displaced in such a way that I also assumed that Travis had begun cleaning his house before getting in the shower. The vacuum cleaner or 'floor cleaner' was found in the middle of his living room, I believe, adding to this theory imv.
Travis was a tidy guy, that seems pretty clear. I do not believe JA would do any cleaning chores when Travis (or anyone else) was home, because I think it was merely a vehicle for in-house snooping/surveillance... there would be no benefit for her otherwise.
Setting aside, for a moment, conversation/emotion - mainly because I have several ideas on that but focusing on logistics for this post:
I think they got out of bed for the last time that afternoon, and Travis put the sheets/bedding in the wash and began to clean his house - while JA appeared to be leaving or preparing to leave shortly. Travis then got into the shower (leaving sweaty black t-shirt and shorts on the bathroom floor) after having seen JA to the door (only she came right back - or perhaps never left, making up some excuse) only to, shortly thereafter, find JA (uninvited) snapping pictures of him in the shower, completely unaware (or more likely unconcerned, even self-satisfied) of how rude and invasive such behaviour is.
I think the towels and clothes found in the washer (at least some of them) were bloody, and JA washed them - ruining the colored items with bleach in hopes of removing blood - something a person just doing a normal load of dark/black clothes and rust/rose towels - would not do.
I think she used the towels and clothes (discarded on the bathroom floor by Travis upon getting in the shower) some of which got bloody from the murder, others used by JA to walk/stand on, keeping her feet clean while getting through the hall (and eliminating any shoe/foot prints in the process), from which she would then jump off of to the clean carpet - in the bedroom or closet perhaps after putting on clean (non-bloody) socks to wear from the bedroom to the washing machine. I think she piled the bloody items just beyond the bathroom hall on the carpet that appears smudged.
She scooped up these items in a clean towel (or other item that she took with her) to contain any blood (that was likely absorbed into the cloth and wouldn't drip) and the camera (after deleting the photos) dousing all with bleach. I think the socks and undergarments may have already been put in the washer by Travis, intending to wash them once he had enough for a full load.
I think JA showered in the shower either standing on or straddling Travis. The shower was already bloody, I don't think she'd want to risk leaving evidence in a first floor shower or the master bathtub. I think she may have rinsed the walls of the shower with the cup.
ETA: Then again, if the master bathtub was spotless and free of blood... it seems unlikely that no spatter, even a little, would hit the tub, so she may have used it and meticulously cleaned it afterwards, but the shower was there and I think she chose the fastest, shortest way to get done and get out, so while possible I think it's unlikely...
I think the camera was put in the wash intentionally in an attempt to destroy it. If it was 'caught up' in the bed linens, it would have been found in the dryer with the bed linens. And I don't believe the items in the washer were large enough individually for a bulky camera to get caught in a shirt or towel unnoticed. The load wasn't big enough for that either. It likely made a racket clanging around in there. Something one would investigate unless they put it there deliberately.
Just a few theories...
What can I say, I love to play with my brain. Feel free to point out any glaring holes in my ideas - I'm sure there are many.
