Grounding your system, as ATL has said, won't be a problem, and probably will easiest be done at your Entertainment Center, inside the house.
However, I am concerned why you are using two Antennas, both which receive UHF. If you intend to connect them to a single receiver, you're going to have a signal interference problem.
First, go to tvfool, create your reception chart there, and paste the bold link back here, for us to help you analyze your reception issues.
https://www.tvfool.com/index.php?option=com_wrapper&Itemid=29
From the looks of your house, I'd use 25' as an installed height.