I've found quite alot all leading to the one spot. I have the UV map. I decided to visit the prison, more specifically, block 9a as mentioned on the map. I found on a door on block 9a, a riddle about the 8 aswell as a small picture I recognised. I looked at the map and found that the picture was a map of the northern most part of the map and the cluster of islands surrounding it. I then went to the abandoned house near trevers trailer. There I found a name (something Abraham), more riddles, 8's and more of the same picture of the pinacle. I also found there several tallys scratched in to the amount of 5 each. Then, completely by accident, I found a small radio tower in the east. At its base was a red truck trailer and 5 men. 1 worker and 4 men in black suits sunglasses and with ear pieces each (5 in total) if you approach them they all start taunting you in a similar way Trevor can taunt other npc's. Stay too long and you instantly get 2 stars and they start attacking you with battons. I found on the back of the trailer a mall gold smudge. It looked familiar so I looked at my map again and it was exactly the same shape as one specific island in the cluster at the pinacle . Mentioned earlier. On the front of the trailer there is an A. Not sure if its significant or not yet. My guess at the moment is if you are at the specified island at 8 or maybe 5, something may happen. I am yet to try. I will post my evidence at a later date. If you have any questions, feel free to message me.
Infinite 8 killer. Just use the "search" function. Already solved.