Back 15-20 years ago we had to deal with GPS signal being scrambled by the US military.. and there were way fewer sat's. I would be bashing my way through the tree's with a backpack and an antenna on a pole. Poking the pole up through the branches. You wanted to make sure you could get something done in a day, so we used to use Trip Planner from Trimble... I imagine you can still download it somewhere... but have a look at their online tool.. GNSS Planning Online You should be able to evaluate how your reception is regardless of which GPS you are using. It will also help you understand why V1 green (gps only) typically gets the 10 or so range of satellites, while the upgraded one sees 20 or better (check the number of sats tab). There's tonnes of useful information you can glean out of this to have as safe a flight as possible... or at least avoid crappy times.