look here http://www.rfactorcentral.com/skins/spraybooth.cfm
You can over write orginal skins so you can use it online with no missmatch .
But best is to do new skins is add a new skins folder to have new skins in you can copy the orginal files rename them no need use templates then if you wanna show your skins you must send the skins to the drivers that you wanna to use and see your skins.
Otherwise they just see the default skins that the mod use when join a server online.
that way you not need upload and install new skins in the server.