If you ever got a good splash of salt water I'd rinse it with fresh. Up on the flybridge should be high enough to avoid any salt water. We never have had salt spray that high being mostly fair weather boaters. Could be covered for storms but I'd just take it inside if we needed to ride one out.
I guess the high output charger and inverter take a lot of room and weigh a fair bit limiting how big the LiFePo4 pack and still be portable. The AC300 model doesn't even have a battery pack and needs the external ones to work.
As a test I've had mine on my boats outside flybridge deck for 3 months now. Here is the update video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nJ0GMoSnMwc.html Cheers, Ray