Thanks to Alex for using his map of all highlighted buildings, its the clearest map I found for indicating my point
Looking at the map now where do people think the Atomic Tyres Blimp airport base will be? In real life it is located just east of the intersection of the Harbor Fwy and San Diego Fwy.
Taking that and applying it to GTA V's map, could be in two places in my opinion if Rockstar simply placed it next to the freeways.
Click all images to enlarge.
This is just pure speculation and guesswork by me, but looking at the Blimp pre-order screen I reckon it the landing base wouldn't be any bigger than half the size of Echo Park's lake, looking at that area on the map, I have highlighted two circles in red where it may be, based on the fact the real life one is close to the Harbor and San Diego Fwy. In reality the Harbor Fwy leads to the western side of the Docks, or the Vincent Thomas Bridge's western side, so the western circle just south west of GTA V's Interstate 5 could be one place, or that little bit of land with no buildings north east of the interchange near downtown.
Pure speculation as I say, and there really should be a landing base as its pilotable, wouldn't be cool to somehow magically be in control of it, without entering it on the ground at a landing base.
Great work guys with the real mapping based on facts.