I installed our bank of 8 Trojan T-105 batteries when we purchased this boat in 2014. We are full time cruisers, and the batteries are still going strong.
We are a bit further N of you in the NNE Pacific, and the
battery temps average in the 50s°F year around. (The battery locker is against the
hull in an unheated midship
cabin.]
Our bank is inaccessible unless hundreds of pounds of tools and spare
parts are moved, so I installed Trojan's manual
remote watering system. It takes me less than a minute to water the entire bank using an
outboard squeeze bulb in a container of distilled water- including set-up and putting things away. The bank only needs water monthly, and then typically less than a quart.
Many more details and links to sources- including photos of the ugly install- on
this post.
Separately, I would argue if your choice is between
AGM and FLA, and you aren't able to bring the bank to 100% SoC weekly, then FLA is a better choice for longevity.
In case this is helpful.
Cheers! Bill
PS: When away from the boat, you can install a gravity tank of distilled water connected to the feed tube of the batteries to make sure they stay properly watered...