Where are the fuses?

Trying to get familiar with the '91 V-20 I recently bought. As you would expect, all of the aftermarket electronics have inline fuse holders in the +12V
supply wire. What I can't find is a fuse panel, or any fuses at all associated with the original factory wiring of the horn, lights,wiper, bilge pump, etc. I'm sure someone here can clue me in as to where they are.
Also, I'm considering installing an aftermarket temperature gauge on my motor (Yamaha 150 2-stroke).
Is this considered a worthwhile thing to do?