This mod from 04mdavitt will add Security Fences around three of the safe houses in GTA San Andreas.
--Grand Theft Auto San Andreas Safe House Compounds--
This mod will turn the three main safe houses (CJ's House in Los Santos, The garage in San Fierro and the air strip in the desert) into compounds with fences around them and working gates, along with other small addins to the areas.
The only thing that may cause problems is the fact that on the outside of the compounds the gates will only open to military vehicles, but the gates will work normally for any vehicle on the inside of the compounds.
How to install -
Simply extract the zip file into your Program "FilesRockstar GamesGTA San Andreas" folder and it will overwrite the original files and replace them with this mod. This should work with all versions of San Andreas even 2.0 as it does not change the size of the gta3.img file. Enjoy!
This mod can be used else where as long as credit is given to me :)