You need to anchor the frame on something that is obvious and reliable, like the roll bar of the jeep. An empty spot above it isn't a good choice.

Next, you'll need to go back and realign the tracker if you see it slip off target. To do that, stop the playback right when you see it slip and then record an update once you've adjusted the position. You can do that frame by frame if needed.

Once that's done, your photo should track more smoothly when you add it in. You may want to search on YouTube or in the tutorials section for more info on how to use the tool.