The new A&S is more land than water now however, you will still have all of the watercon aspects when you get to predive. So I would absolutely not stop practicing your water work.

Start rucking a lot. Get very comfortable wit 60 lbs on your back. Also focus on load bearing activities (i.e Farmer carries, Buddy carries, Training aids)

Start at 35lbs and work up to 60 lbs.