Unless the only car seat you have available to you is an infant carrier-type seat, meaning it MUST be rear-facing, then I'd suggest that you'd be fine with your child forward-facing for flight, and you can use the seat rear-facing again in the car at your final destination.
Traveling with two little ones isn't a walk in the park on a good day, so I wouldn't make it any more complicated than it needs to be. I think you can feel good about choosing the right flight time, route, etc., and forward-facing the seat (assuming it's a seat than CAN face forward).
Besides it seems like lots of airlines change their tune on car seats from one minute to the next. Web site says one thing, FA says another, check in staff just shrug and mumble...