Hi
It is pretty safe to experiment with the config.
1) Make a new mod folder like MyMod.
2) Copy OFP/Res/Bin folder into your new mod folder.
3) Now get those config.bin and resource.bin files into .cpp format, use a tool or grab files from some mod which has already done that for you. I'd use the default RES files so you have a fresh start.
4) Now you have resource.cpp and config.cpp in the OFP/MyMod/Bin folder which you are free to modify.
5) Start by examining resource.cpp, as I remember it containts the stuff defining the user interface.
6) Modify the files to your liking and start OFP with MyMod folder and that's it, and no original files were harmed in the process.
Using those config files you modified could cause problems in multiplayer: others will get a notification that you are using a modified config file and could take that as you are cheating. This problem goes away if you make your own mod and make everyone in the server use it