So it's time to get my comet gp-3 in the air, I'm wanting to use an eave mount(
http://dennysantennaservice.com/1079223.html ) using schedule 80 rigid conduit as my mast. (
http://www.lowes.com/pd_73207-1792-101093_4294722503__?productId=3129615&Ns=p_product_avg_rating|1 ) I have a swap cooler dead center of my roof line ( can't wait to see what kind of RF noise that thing puts out

), But my plan is to have the base of the antenna above the top of the cooler buy about a foot witch will have roughly about 6' of mast above the roof line. Is 4' in the eave mount enough? Is there a rule of thumb on how much mast you should run under the roof line VS above? Do i or should I guy the mast some were above the roof line?