Checking bags back to the original destination without clearing customs

I'm travelling on a Qantas flight from Orlando to Dallas and then onto Sydney. I then have a Sydney Dallas, Toronto flight on the same day after picking up my family. OK, first of all, before you ask the obvious question, it's because a) I'm an idiot, b) I booked the Toronto flight before I knew I needed to be in Orland the week before c) we have upgrade requests that will most likely be granted if I'm there (Platinum), but not if I'm not and I don't fancy greeting my wife in Toronto, having flown in a PE seat with a 1 yo alone for 22 hours...

Anyway, my question is, has anyone had bags checked through to a return destination without clearing customs, etc. Staying plane side would save a lot of hassle and reduce the risk of missing my connection (although I'm probably getting back on the same plane)

Honestly, even if the airline would tag the bag for you for the entire journey, I suspect the scenario and that type of tag would be so rarely seen by baggage handlers at Sydney Airport that they'd probably see DFW SYD DFW on the baggage tag and just offload it in Sydney. If it were any other destination, you'd have better luck as Qantas does handle international-international connections in Sydney, but I suspect your luggage may accidentally be offloaded and then left in Australia while you're flying back to the US.

Much safer to either collect and re-check in Sydney (even though you shouldn't technically have to), or to ship/courier/freight your suitcase straight from Orlando to Toronto and have it delivered to your hotel.