I doubt you will be able to just bounce the signal off hill. Best would be to place a active repeater there but then you have the issue of needing power.
First thing to try is to get on top of the hill you want to bounce the signal off and see if you can even get a signal. You will likely have to use large directional antenna. If you cannot get a usable signal then it does little good to try to extend it from there. I would not even try it unless the signal was strong.
What you can do is use 2 direction antenna hooked back to back with a very short piece of microwave rated coax cable. You would point one antenna at the far location and the second at your final location. You would likely need direction antenna pointed at your...