Breaker and in-line fuse questions

[Radiozephyr]

I’m planning to install a i70s instrument pack, as well as a EV-200 autopilot, and I’ve run into a question I can’t seem to solve. I’ve decided that I’m going power the SeatalkNG backbone independently (i.e., not through the ACU-200) by running a SeatalkNG Power Cable from the iTC-5 to the “Instrument/Radar” breaker on my breaker panel. I plan to check the rating of that breaker, and will replace it with a 5 amp if it isn’t already (is that right?).

My question may seem a bit obvious, but I can’t seem to figure it out: how do I install a fuse for this connection? The manual is clear that “the distribution point should be fed from the vessel’s primary power source by 8 AWG cable,” and that it needs to be protected by a 5 amp fuse. However, I can’t find any in-line fuse holders that use 8 AWG cable and also can hold a fuse as small as 5 amp. Am I totally wrong to think that adding a fuse holder with a smaller gauge wire will create a bottleneck?

Also, the autopilot should be connected to a 20 amp breaker, correct?

Thanks!