Hi
@Misstonz,
there are three models of Setec, each with a separate manual. You have a MK II Setec, so ensure you download the correct manual. Beware though that the updated manuals do suffer from not being updated correctly and contain errors.
You can download the correct manual from the Setec site:
http://www.setec.com.au/pdf/ST-II-User-Manual.pdf
The nice pretty label showing what the fuses do is probably wrong. It is just a generic factory label and not necessarily specific for your van. It is worth spending some time to sort out once and for all what each of the fuses is for and making up a new label.
I would suggest pulling all 5 fuses out on the left.
Then have a look at the wiring at the top of the unit and you should be able to determine which fuses have been connected.
Then insert one (connected) fuse at a time and see what is powered up. There probably isn't much: interior lights, exterior light, electronic ignition for the stove, interior and exterior 12V sockets.
You haven't mentioned what you want to hook up. The power draw of what you want to connect may determine how you may want to proceed.
If the power draw will be minimal (less than 5A) then tapping into the most convenient circuit may be the way to go. If the power draw is less than 10A you may be well advised to feed it from a spare fuse if one is available. For higher current draw you would be better to run a suitably sized cable directly to the battery terminals (assuming you have a battery) and wire in an inline fuse close to the +Ve battery terminal.
Note that the maximum rated output from your Setec charger / power supply is 20A.
cheers
Mike