Layout recommendations are typically in relation to the main listening position, hardly ever for a full row of seats (let alone two rows). Dolby's install guide for home Atmos is no exception, since all the elevation and azimuth recommendations are based on a single MLP.

Since you have a 7.1 set-up, with surrounds already elevated, I would place the height speakers so that they are angularly separated from the other speakers. The front pair of heights can go in the gap between your front and side speakers; the second pair of heights can go in the gap between the side and rear speakers.

To keep the height speakers from overwhelming the closest listener, I would point them at the listener furthest away (a little time-energy trading). So, for example, the front left height speaker would be aimed at the listener at the right end of the back row.