Maybe you could add like snow in some parts of the map, so it would be more challenging. Also, would it be possible to add snow particles like in mammouth valley?
Floating point calculations. Essentially, the game uses coordinates with a set amount of digits so when you get further from the origin, and increase the number, accuracy goes down. Example: 10.33334 is much more accurate than 10000.33. So when the game's graphics engine is trying to figure out where to display car parts etc, it jumps around more due to the inaccuracy. Alot of games solve this by just moving the map around the player. I ran into this issue on my 20x20m mile map for my BeamMP server but we decided to reduce it slightly and just deal with the jitter considering the type of server it is.
I had to edit the plane with F11, because the terrain is located 441 meters down from the starting point in the barrack. Before this mod of mod, as I exit the warehouse the Gavril pickup fell off. Then I lowered all Tsstatix to Z=0 but leaving X and Y axis unchanged for each object. This terrain has not hills or mountains.