Unsure if I should try

Hello,   I have done a bunch of mile swims in the ocean this year and a bunch of sprint triatholons. I currently swim about 2200 meters twice a week in a pool with a local masters group.  I have swam all my life.  If I do the swim I would wear a wet suit but I am a little intimidated.  How much do people currently train for the 3 mile race?  What is the current like?  Do we get in the water in the a.m. or at noon?  Sorry for all the quesitons.  I would LOVE to do this swim-- just not sure about the the 3 miles.  Any words of wisdom?  Thanks, Stacey