Jusupov has released a mod that FINALLY allows just cause 2 players to complete the game with 100%, the proper way.
"This mod adds the missing watertower at the correct location (X:18111,Y:15326). It also adds the 3 missing vehicle crates and the 3 missing weapon crates to the same area. These combined allow for 100% completion." - Jusupov
You must have the world location settings mod in order to use this mod first, Download this First
100% Completion Mod