Installing ignition relay

I have a fuse link in my charging line, that’s an 8 gauge wire with a 12 gauge fusible link.

What I’m wondering about is protecting the original factory circuit, which presently is “protected” only on one side and only by the factory fusible link.

Should I add in line fuses to each of the red and black wires in the engine compartment? If so, what amperage?

Even with the relays I have installed I’m pretty sure all of the wiring coming into the car is unprotected (except for the factory fusible link) powering the fuse box and accessories and including all of my under dash wiring.

BTW, aside from my stereo and amplifiers, which are protected and wired independently of factory wiring, I have added no other electrical components. Rear window defogger system has been removed.