Adding a fuse is recommended anyway.
I think it should work fine. An alternator doesn't push 60-80A, it depends on the connected equipment what is actually pulled. A regular AC socket eg also doesn't push 15A, it only means it *can* provide 15A when requested.
I fully agree the PV is limiting the current by default. Even at the worst case of a almost fully short, the panels can't provide more amps, unlike the alternator, which can probably provide more current. (Overloading the wires, and in worst case also damaging the MPPT, depending on it's design).
I think we can agree it *might* work but it's not recommended.