Seems once again this just boils down to the 'Dirty Harry' question again ...

If you do feel lucky then go for it and let us know what happens.

Be prepared to pay the cost of a new one-way flight with a happy smile if it turns out you were not as lucky as you thought, or return and tell us how it all turned out to be easy ...

Only experience I can add to the mix is on an itinerary ticketed by AA that involved AA, then JAL, then KAL, with about a 10 hour layover between JAL and KAL. When we tried to continue our trip by checking in with KAL we were initially denied as they could see we had not flown the JAL leg so our tickets were cancelled ...

It was actually a mistake and did fly the JAL leg and we managed to get the tickets reinstated, but the ticket had certainly been cancelled due to an apparent failure to take a JAL flight on an AA ticket and only 10 hours had elapsed.

When considering your level of 'luck' factor in that you have to check bags I believe so there is no way to avoid an interaction with an AAgent, and it should be pretty clear to them at that point what you have done.

Given attempts to skip this flight are far from uncommon on this route they will be familiar with this and will know what they need to do...