Oh, it's possible! here's a video of a test flight I just made last night using a Phantom 3 extended range antenna kit from FPVLR. They call it the Phantom 3 Advanced antenna kit. The "Advanced means that they added WiFi boosters to their regular kit and has nothing to do with Phantom 3 Advanced vs. Phantom 3 Pro. This kit works on either. They also offer installation with one day turnaround if you don't feel comfortable installing it yourself. Tony, the owner, is currently on Vacation until the end of July 2015. Then he will resume taking orders.
Here's my video: Please read the description in the video for more info. Where I used to only reach about 3000 feet, I now can go over 3 miles. That is a 600% increase. If the battery lasted longer, I could have gone further, my signal was still strong.
How do you keep signal with all trees in way? I noticed you were sitting under a carport with trees around you. I know trees blocked line of sight. I have a Intelelite antenna kit on mine and I got around 5K but had to be in open.
In the direction that I was flying, it didn't have a problem keeping the signal even with the trees and changing landscape. And yes, I was not in an ideal spot during takeoff, but I did maintain video feed and a strong RC signal for the entire 3.1 miles. I had plenty of signal to go further, but my battery had other ideas.