Today I went to 24 Hour Fitness to get kind of a baseline in the pool.
I know swimming 1.2 miles in the open water is much different than swimming some distance in a pool at a club, but some conclusions can sort of be drawn by swimming in a pool.
A mix of free and breast strokes got me to 62 lengths! I didn't take any long breaks. I think I did stop at the turn walls maybe 5 or 6 times for a moment each time. Of course in the ocean there are not any walls to hang on to - you can't take a break or get the added benefit of pushes off of the walls at turns.
I know there is some pool work to be done. But the swim of 1.2 miles should be OK.