My kids are 6 and 3 1/2 now and we went through the same difficulties with headsets when they were younger. I think your daughter grow into wearing a headset shortly. Our trick with my daughter, the 6yo, was to buy her a purple headset for a Christmas or birthday present, I don't remember which. We made a big deal about how special they were and that did the trick for her. My son, 3 1/2, still is 50/50 on wearing his red headset. He just doesn't like any headset really. My wife's car has a DVD player with wireless headsets and he will sit and watch a movie with no sound rather than wear the earphones. I do make him wear ear plugs in the plane if he chooses not to wear his headset. When your daughter gets a little older, soon, she'll understand that there are rules and choices and she will make her choice of headset or ear plugs.
Upon arriving at the hangar, the car seats come out of the car or truck and go straight into the back seat of the plane and the kids load into them just like the car. The youngest is still in a regular car seat and I use the strap that has the clips on it, that hook into the latches in your car, to hook it into the airplane. I connect those clips directly to the bracket that the seat belt mounts to the airframe with and don't actually use the seat belt to secure the seat.
The combination of the headset and car seat become a pain for the kids on long trips. When they fall asleep in their car seats they have a tendency to turn their head to one side but the headset doesn't allow for that really. I'll have to look and see if I can find some pictures of the contortions my daughters been in. She always finds a way to sleep though.
Keep taking your wife and daughter with you. We use the plane to travel a lot and the kids love the journeys. My 6yo probably has 300 hours or a little more and the 3 1/2 yo probably has about 200 hours in the back seat. One of our frequent trips is a 2.7 hour flight or 8 hour drive. We've had to leave the plane and drive home one time because of weather. The kids understand the travel time difference between the airplane and car now very much and always question why we cant take the airplane everywhere.
We have a portable DVD player but honestly never use it or even take it with us in the airplane. The oldest has a Leapster game that she'll play sometimes. They both like to color/draw on the knee board. If they're not sleeping and there's something to see we try and keep their heads out the window. We look for deer, bears, moose, farm animals, farmers working their fields, and whatever else that might be interesting that we can point out to them.
I have BW's...He has Air Hawks. Both very good aircraft.
...that means no landings for me at that altitude with winds like that. It did however make for some good up drafts and fun flying as long as I was on the good side. Flew around looking at a bunch of our landings on the "East" circuit. All of these are above 9000'.
Great thread!!