Rear sun shade for baby?

I’ve got a 2023 RTL-E and a 2024 infant

He’s in a rear-facing car seat for a while and the giant back window is really difficult to shade when the sun is angled through it on a long interstate drive

Anyone found a good accessory for this with the 2nd Gen? I have a Munchkin stretch to fit mesh shade for the door window, but the magnets don’t work on the back window.