2019 non-removable back headrests & child highback booster seats

Hi All, I am seeking advice from anyone with a 2019 Tesla Model 3 re: how to use a highback booster seat for a child in the back seat. The 2019 does NOT have removable headrests in the back like newer models (they're stitched in place), and the headrests lean forward in a way that hinders the straight back booster I currently have from laying properly. The middle seat doesn't have lower anchors, so it isn't the most ideal positioning either. Any advice about how to make this work is appreciated-- or specific booster models. We need to use a high back booster, not the backless, for my kid's current size. I tried searching here for other posts about this but wasn't successful.