What size Breaker in your AC Panel fed from Solar Inverter

I am totally off grid.  With my current old system the inverter feeds the main 100 Amp breaker in the cabin panel via #6 conductors in conduit.  I am upgrading my solar system and my new 6000W Inverter will limit output current to 42A continuous (–90A surge).  I know the 100 Amp breaker in my panel is oversized. My panel is a Federal Pioneer (Canadian - not the same as the US version with issues) the 100 Amp main breaker cannot be swapped out.

I would still like to get the breaker in the panel to the correct size which I believe should be a 60 Amp breaker but would need to do a panel upgrade to go to either a 60 Amp main breaker or a 60 Amp backfeed breaker.  The new 100 Amp panels allow you to swap out the main breaker so could put a 60 Amp there.

Wondering how others off grid have their panel and breakers wired?