I had some difficulty getting the two on top of the "disciples" on the map (link here:
https://drive.google.com/file/d/0Bx56OMD1DBiVOGFEV3NESzhPbHM...).
The way I got them was to select the Ford Raptor, since it has 4 wheel drive. I would drive to the edge of the cliff to line up with the board. Then back up in a straight line a sufficient distance so that the exit velocity off the cliff was greater than 100 mph. Once on the cliff, I would use the four wheel drive to climb to the board and knock it down. Here is a video of me knocking down the disciple the southern disciple:
For another one, I used the Ariel Atom and lined up to get an exit velocity of 100 mph. Here is a picture that shows the location:
https://drive.google.com/file/d/0Bx56OMD1DBiVclExWHF0dWFaREk...Unfortunately my liftoff was not true, so my attitude into the sign was not great, but I did hit the sign. Here is a video of me knocking it down.
For the one in the middle of the lake, find a small channel that is shallow and drive to the center island. Then navigate to the other smaller island and knock over the board. I placed a picture of the map on where to go.
https://drive.google.com/file/d/0Bx56OMD1DBiVOFo3ZXc0dHc2Unc...