KISS applies. Mossberg 500, slugster barrel, Brenneke slugs, slung in an Alaska Sportsman scabbard. Works great, easy to carry or to draw. Leave the frills off of it and leave the $1,500 co-pilot at home. Assume whatever goes down the river with you will be in and out of the river multiple times.
While bears are a minor concern in Alaska, Moose are actually responsible for more injuries and deaths. TBH, I'm less concerned about bears than Moose, and .223 is simply inadequate for m005e. (A m0053 bit my sister once. . .)
Not sure where that info is coming from. I'm only aware of two moose fatalities, one of which was entirely avoidable and the other I don't know enough details of. I've been chased by many, many moose and run into them at close quarters all the time. They just want you out of their space, and are only a threat if provoked. Even then they don't represent the threat posed by a griz on the Yukon. Not even close. They're amiable creatures and very good eating.
When you say things like this, you get folks outside paranoid about moose and they're liable to start blasting them on the trial on sight. That's a freezer full of meat wasted by some fool cheechako. Not to mention the very real possibility of criminal charges and jail time. Juries here do not like bear much, but a moose is someone's food for winter. You'd have to hope for a jury of gardeners.
Also, moose don't take much bullet to kill. I've seen them killed with 7.62x39 SP's. They usually take a minute to die, but the heart/lung area is enormous on them and a very easy target. Killing moose is not half so hard as getting them butchered and packed out.