Greetings,
Twenty-five foot is definitely the way to go. Your signal access is improved over 6'.
First consideration: trees. Are you surrounded by them? They can make successful reception even in strong signal areas problematic.
Second consideration: multiple headings. You have a mix of high-VHF (real channels 7-13) and UHF (14+) at your location. This requires some careful equipment selection. Greenville gives you the best chance a full set of major affiliates.
If I were to attempt an installation there would be two approaches I would consider. The first if I wanted a single antenna solution would be an
Antennas Direct Clearstream 2V. This antenna would be orientated to magnetic 025 (NNE). It supports high-VHF and UHF and offers a reasonable beamwith. You have a reasonable chance of seeing the major affiliates.
If a 2 antenna system was needed. I'd purchase an
Antennas Direct DB8e for UHF channels and a
Antennacraft Y10713 for your VHF channels. This would require a combiner to unify the antennas into one coax coming into your home. The Antennas Direct EU385CF works well for this. The DB8e would point to magnetic 025 and the Y10713 about magnetic 020.
Channel master makes a distribution amplifier that, once your coax comes into a central point in your home, at the split point this amplifier offsets signal loss from the split and coax run.
This is this unit:
http://www.channelmaster.com/Antenna..._p/cm-3414.htm
Cheers.