Wel as far as I know Fuse F5 is for the backup tension (12V permanent.).
I use it for the remote door opener backup radio clock alarm.
On the fusepanel it is fuse F5
It also give the blinkers tension.
The electronic stuff like alarms and backup radio and clock don't ask much current.
Only automatic deuropeners us e a bit for the moment it opens.
The blinkers all around use 2x21W + 2x5W if alarm lights are on, wich is 4.5 Amp
Fuse F5 = 16 Amp, so not much problems to expect if you put some stuff on it
Maybe that anwers a part of the questions