Review on 🌊 Waterproof Rear Bench Seat Cover - Motor Trend AquaShield Gray, Padded Neoprene Car Seat Protector for Kids & Dogs - Ideal Interior Accessory for Auto, Truck, Van, SUV by Robb Fillmore

Has slots for seat belts/child seats. If you want them to be more customized this neoprene seems durable enough that you can cut it yourself and tie it with tape if needed. The block is all one piece so if there's a wet dog or a bathing suit around it won't slide off - very good protection. It's thick enough to get the job done, but thin enough that we could leave it in place and fold the rear seats down in the Tundra.