I used a 10g wire from the alternator to the ammeter, so my 30 amp CB is under the dash before the meter. Used a 30amp for 2 reasons. First, it was the only one I had in my used parts box. Second, to protect 10g wire you should use a 30 amp fuse or CB.
I wired my Jubilee about 4 years ago and yet to have any problems. Lucky if my alternator produces 20 amps on start up. Had to replace the 40 amp alternator because the bearings went out. I went with a larger alternator. Still no problems with CB.
When I changed the alternator on my IH C, I used a 30 amp fuse on the alternator wire because I didn't have another 30 amp CB. NO PROBLEMS.
When I told people I was fusing the alternator wire, some thought I would have nothing but problems. Glad that you agree that alternator wires should be fused.