Channel 5 and 6 are in the low VHF band and that translates to long antenna elements being required to receive those lower frequencies.
How about this for a VHF only solution?
http://www.summitsource.com/antenna-...00-p-7101.html
Also, given the relatively short coax run, amplifier gain does not need to be that great... The amplifiers primary job is to overcome losses in the cable and splitters. A Winegard AP-8700 has more than enough gain and omits the UHF input of CM7777 which you would need to terminate in a VHF only install.