If you choose to limit yourself to the ICW, it has a controlling height above the water of 65' except for one bridge between Miami and Ft Lauderdale which is 56'. To see more details just google "icw controlling height".
I have not seen a design mast height for a HP, but my guess is that given a quoted sail area of <1000 sq ft for the HP50, split between two masts on a schooner rig, your mast is going to come out under that anyway.
A rough back of the envelope calculation for a 500sq ft per simple triangular sail gives a 20' E and 50' P. Given you'd have some roach, the E and/or P will actually be less than that for 500 sq ft. Add 10' for bury and from deck to tack, that gives 2 @ 60' masts.
Mark.