I use this for my sweaty kids: https://www.amazon.com/gp/product/B01KNWU66W it's completely waterproof so the funk doesn't get through.

I have black seats on my model 3 so can’t say how this works with white, but I can’t see why this would cause any issues.

I got these seat covers because I was going to the beach a lot and also the gym. What I like about them is they have a pocket that goes over the head rest so they are easy to put on and take off.

My housemates have a kid so I’ve put this under the car seat when I’ve driven her around in my car and it worked well and I didn’t have any issues after leaving the seat in the car for a week.

Leader Accessories Black Waterproof Sweat Towel Car Front Seat Cover for Truck SUV Bucket Seat Dog & Kid Non-Slip Auto Protector https://www.amazon.com/dp/B01KNWU66W/ref=cm_sw_r_cp_api_glt_fabc_JQEHA5MS9PEJFCW7DJSQ?_encoding=UTF8&psc=1