You are overthinking this. All of the individual accessory circuits, with the exception of the charging circuit, are protected with either fuses or circuit breakers. A fusible link is designed to protect against a gross overload of the entire electrical system. Replace your fuse with the correct fusible link and then start troubleshooting. Having the fuse in there is only muddying the waters.

"We live in a time when intelligent people are being silenced so that stupid people won't be offended".