yes county fair is THE cuke to grow.
like you my plants would die in the 2nd or 3rd week of august. i tried different varieties but when i found out what was causing the (BW) i grew county fair for several seasons and i now get TONS of cukes all summer. this past season my plants were producing into the final week of september which is very late. by the 2nd week in september the plants typically are dying. i suspect this is due to a weak sun and shorter shorter days.
i'm stubbornly organic and would never use sevin and there's no reason to, grow county fair and you'll be in pickle heaven. i use them as a slicer and they are great tho the skins are a bit tough and slightly bitter so i peel them. i don't like to peel them but it beats not having any to peel!
county fair is not easy to find, parks has them and i think a couple of other places but it is not found just anywhere unfortunately. there is another pickle i never tried that is supposed to be BW resistant that shumway sells. if you need more info let me know.
tom