Yes - this works brilliantly. Don't even need a child - just a female companion, stretchy t-shirt and a pillow. All that hard flying year-in, year-out to earn status and our last trip as a two-person family with my wife 6.5 months pregnant and we end up boarding before the group one on my boarding pass is even called.

The pillow is probably cheaper than a carpet bag. The female companion probably less so. Mine cost many dinner dates, a quite expensive ring and an even more expensive gathering of friends and family involving a church, a barn, music, alcohol and another ring. Of course, if you are already female, you're quids in. You could probably sell your companionship to the OP for the price of a carpet bag and get them on board in group zero with you as your 'partner in parenthood'. Hmmm. I feel like the phrase"selling companionship" may raise some red flags among the moderators....