Attics Are Not a reception friendly environment and Never Will be a reception friendly environment.
The metal backed Radiant Barrier will cause reception issues , reflected signals bouncing around in the attic , multipath.
Yes you can try the ANT751 in the attic aimed at about 202 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
Yes remove the Radiant Barrier and get the ANT751 antenna close and aimed through the hole.
I recommend try reception without the preamplifier.
The preamplifier will amplify the reflected signals bouncing around in the attic off the metal backed insulation and can make reception worse.
WPXA-DT UHF Digital channel 51 is the odd one out , because of the direction of the transmitter , and will most likely will not be received in the attic.
The metal backed radiant barrier will most likely block the signal.