Hi there.
I was thinking about it some time ago and, as i am just a 3D a modeler and i don't understand the GTA Editing in itself quite well, i want to discuss the possibility to contour the GTA engine limits and break the map size limits to infinite size (or any size we want). I want to reminder that i don't have plans to make a HUGE mod, but i think that conversation will drive us to something constructive.
At first,
As far as i know about GTA is that any GTA have its co-ordinates limits (maximum co-ordinates numbers at X, like 0.0000 to 546.0000), and any of these co-ordinates are a float number (float number, for dummies, are a non-integer number like 2,5; 7,543; 35,374...), and, by the logic, inside a float number has infinity other float numbers (i.e. inside 5 we have 5,2; 5,54; 5,65, and inside 5,2 we have 5,23543; 5,22423; 5,2856756...).
Following that logic, at a co-ordinate number, we have infinite numbers inside on it. Think about instead of trying to raise the co-ordinate numbers limits, multiply a 5x5 co-ordinate grid by 10 (50x50) just by constructing your new mod with the models 10x smaller than the normal size, and editing anything you need on the script and data files to fit camera, handling, and etcetera and making every thing fit quite well in just ONE co-ordinate number. Double your co-ordinate number capacity by shrinking objects. That is my first point.
...........................................................................................................................................................................................................
At second point,
We all know how house interiors works. It has another 16 or 17 worlds for the interiors and just ONE for the outside, conventional map. When we cross a door in game, we are crossing a portal that drives you from World 1(Outside) to any of 17 interior worlds.
As GTA San Andreas already did with Liberty City, and GTA V already did with a country town, why can't we just model another map inside one of 17 interior worlds, and use a big portal on sea (Like a big door) in two worlds to drive us from one world to another? Basically transforming one interior world to another exterior world (a new map) and keep the world 1(default map) intact. Think about that. It is possible at some way.
About the first possibility (keeping co-ordinates and shrinking objects) i already saw a example used on Source engine (Which have a very limited map limit) and it worked. The guy extended the map limits 10x just by shrinking everyting 10x. About the second possibility, is is also a plausible idea.
Well, thanks for attention.