Dublin could and should work. A tie in with Aer Lingus, perhaps pushing the trans-atlantic route with the benefits of clearing US immigration before flying.
Pains me to see DTV in the situation it is. Used it frequently in the late 70s/early 80s to and from LHR. Standby tickets at £25 and never not managed to get on the early afternoon flight on a Friday. IIRC full fare was £50 back then, the same as Stobart are charging CAX-SEN later this year?