Our existing Land Cruiser System is 13inches total height, which leaves 28inches overhead. This is driven by the 2nd row seat height when folded, which obviously is different on the Rivian. We will be using our 100% self supported sleeper sliding mechanism (as used in the our 4Runner and FJ Cruiser systems).AirDownGearUp - approximately how much headroom would your system leave in an R1S? Thanks!