Hiya. Quick question, when sizing cable and fuse for an inverter, should I be sizing for continuous power or peak power?

I have the Victron 12v 250w inverter with continuous power of 200w and peak power of 400w, connecting to a 12v 405Ah battery array with a cable run of less than two meters both ways.

Here's my (possibly misguided?) calculations... assuming I'm looking a peak power then 400w divided by 12 volts equals 33.4 amps. Then divided by efficiency factor of 0.87 equals 38.3 amps? Added on a 25% safety margin to reach 47.9 amps. The maximum cable size for this inverter is 10mm so I'm figuring a 50 amp fuse should be sufficient to protect this size cable?

Was planning on using 35mm cable for the battery array to future proof any subsequent upgrades.

If anyone can confirm I'm on the right track or if not kindly put me on the right track it would be much appreciated. Also are there any definite guides for cable and fuse sizing out there please?