Great achievement flying stock. You got bragging rights. I have probably flown 36000 feet stock out of the box by fluke one day just because I felt like losing my aircraft.
The only problem is that this is akin to performing a stunt with no safety equipment. Fly far - lose your signal. Then wonder how long before you see life on your screen. The P3 will limp back RTH at 15mph - if you don't get your signal back it will land somewhere at 10% battery- it will never get back to your home point due to your distance flown out. Unless you have tracking on board you won't know where it is or what happened to it.
Not trying to be a party pooper - many have gone through this journey and learnt the hard way. If you are flying far don't hedge your bets on the signal been there with a parabolic booster just to be 'stock' - take maximum precautions and arm yourself with the best chance of a failsafe. Improve your signal so you have 15 mile range but fly only 7. You are then creating redundancy.
I am no expert but with over a 100 long range flights near enough a million feet in distance (in total) I have experienced all the ups and downs of this hobby. This is not just with the P3, done this with the Inspire 1 and M100 Matrice.
enjoy..