You might try borrowing or buying a coax tester. It lets you install a plug on one end of the cable and then you can find out which cable feeds it with the meter.
We have had a automatic dome type antenna on the roof and now a fully automatic triple LNB Dish antenna on the roof. If I actually get to a spot I can't get reception, I'll break out the dusty old portable dish and give it a try, but I hate aligning that thing. DW and I used to call it the Divorce Dish because the difficulty or ease in finding the signal usually set the tempo for the rest of the vacation and the majority of the time it was neither of us speaking to each other anymore. The roof antenna saved our marriage! :B
I know every region is different, but I have never been in a spot I couldn't get a signal because of trees - Mountain ranges yes, but even a portable can't see over a mountain. That Dish 129 satellite sets pretty low on the horizon out here. We did get issues with rain on our dome type, as the signal cannot be seen through the film of water.