I'm located about 90 miles southeast of Jackson and I am also in a valley. Using the Channel Master 4221HD and a Winegard AP-8275 I have no problems with my local stations overpowering the tuner. The two closest stations are at 014 and 038 degrees and I keep my antenna aimed at the Mobile/ Pensacola area. As they have a better choice of channels and programming. Antenna is aimed at 121 degrees and I am still able to receive Biloxi stations at 145 and 161 degrees.
Try connecting your antenna, Without the preamp, to your television and do a scan. Then rotate your antenna for the best reception on WJTV channel 12. I have found that the 4 bay antenna have multiple lobes and a direct line-of-sight aim toward the tower isn't always the best signal strength or quality. Once you find a sweet spot for Channel 12 then connect the preamp and recheck your headings. Your 4 Bay should have a good 60 degree window or more. I can occasionally receive Channel 12 off of the backside of my antenna when pointed at 121 degrees. WJTV is a 315 heading. Nearly 180 degrees and I believe it's using the horizontal elements for VHF reception.
Electron and GroundurMast have far more experience here than I do. Electron's 220 degree heading looks like a really good place to start.
My TV Fool is here:
http://www.tvfool.com/?option=com_wr...267e3216c4a823
And my Rabbitears TV DX profile is here:
http://www.rabbitears.info/dxlocation.php?id=132
All accomplished with the top of the antenna mast at 15 feet above ground level.