I'm with Bernies first post.

Forget SS and fibe. For one trip, a clean lightly oiled blued steet walnut gun will not show any rust/warp.

Costal bears are bigger than interior grizzlies and you are hunting a MOST difficult way. On the get the small boat and go for a beach shot, you MUST anchor the bear. MUST. the adjacent land will be thick stuff, difficult to track. In AK if you hit a bear, you are DONE. If you just wound it and can't find it your hunt is over. Even trying to take a second bear is poaching. So you must put it down.

Get the largest rifle you can shoot accurately. 458, 375, 416, 45-70. Try to use a shooting stick or get to a sitting or kneeling position to get your best shot. On my two bear trips to Alaksa I used a 416 Rem mag m-700; with a rem custom shop walnut stock and heavy weight blued barrel. My 400 grain reloads killed 2 grizzlies. IMO it is just the best brown/grizzly rifle around.

Sounds like a great trip, enjoy it.

should have added practice shooting offhand/sitting/kneeling....sand bag practice is of no value.