Is it possible to use VNC / ScreenShare OS X 10.9 Mavericks OSX Server 3.0.1 Local Network User
Do you use network accounts (no home folder on the Mac) or mobile accounts (one Home folder in /Users) ? You may be able to add authorization for the VNC/ARD service for mobile accounts with the kickstart command :

sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -activate -configure -access -on -users YOURUSERSHORTNAME -privs -all -restart -agent -menu