Welcome!!
My first thought is if 3-5 acres of watershed will keep a pond that deep full....In my area, 15 acres of watershed is needed fo a surface acre of pond.....No doubt you get a lot more rain than me though. Regardless if a 6" pipe will handle a good size rain event or not, build a more than adequate emergency spill way for the torrential hurricane rains you are sure to get.
It is a very nice setting you have to work with!!...Please keep us posted on your progress!
