Removing them cant hurt. Trojan says to avoid freezing temps. If you cant avoid freezing temps keep them at a high state of charge. But trojan also says to avoid keeping the batteries at a constant high state of charge.
If the batteries are easy to access and it helps you sleep at night then store them at home. If buying new batteries doesnt break the bank then maybe the effort is not worth it. Would suck to hurt your back trying to remove a battery when the life expectancy wont be significantly increased.
I remove my batteries to save money (hopefully) and helps me sleep at night.