It might be eaiser to pay for the towing, and their diagnostic, then take your truck to another dealer W/O the Edge and boost elbow/turnbuckle.
No they can't just void your warranty because they see the Edge (unless it was the Comp and the pump wire was tapped). but it is the standard to deny all calims.
You may end up working your way up the dealer management, then you will hear "You will have to take it up with Dailmer Chrysler, we do what they say, and they said no warranty. " Then you start working on DC. A month later you still have a broken truck, and will be impatiently waiting for the first response from DC which will be a general form letter apologizing for the fact that your warranty was canceled and it will not be reinstated. 6 months later you get a lawyer and you go through the motions of taking their butt to court. A year later your lawyer calls you as says that you may have a court date in a couple of months, and could you please pay the last statement for the fees. 4 years later and several appeals by both parties, DC finally agrees to pay for the repairs and reinstate your warranty retro back to the initial cancellation date, which has now expired.
I would hope that they did not make any notes in the DC database when you took it in about the warranty coverage, and take it to another dealer. If you did get red flagged, I'm sorry for you, and good luck. You have a real strong case that the dead LP killed the VP (they have a very looooong history of that) and not the Edge EZ.