So I did these two together. The “flat floor” seat extender is 3 panels, you can even fold one over the other and free up one passenger door seat in the back.

kmirepa Back Seat Extender for... https://www.amazon.com/dp/B0BDLHT432?ref=ppx_pop_mob_ap_share

Plus these: Durapower Dog Car Door... https://www.amazon.com/dp/B0972KC6Z3?ref=ppx_pop_mob_ap_share