When the car was up on the lift I held the cardboard where it had been under the car so he could see just where the leak spots were coming from. Since this started back in August when I hit the deer when before there were no leaks at all I had put the cardboard underneath several times and it always leaked in the same pattern as the one I just did.It leaks only a few drops after your 2-hour, 100-mile trip, so I don't think a bit of idling would show anything.
Stay with your normal driving pattern and cardboard technique. Leaks can drip to the ground far from their origin, but knowing where they fall can at least give a mechanic a starting point from which to trace backward.
If the leak continues to be elusive, have the engine bay and front chassis thoroughly cleaned to help the mechanic spot the source.
The mechanic did say that he had thoroughly hosed down under the chassis and didn't see a leak.
Damn, that was my bragging point about the Odyssey, that it was parked in the same place for 10 months in front of my house with no sign of any kind of leaks on the pavement.