Is OP comfortable with positioning flights? Flying AA would be a better idea, as DL nonstop between MIA and NAS is really expensive

OP needs to factor the additional cost into the equation, along with risk tolerance (getting there the night before would mean hotel costs; getting there the same day, if possible, would run into potential risk of no-show - this is especially problematic involving international flights repositioning).

I would do it to save a boat load of miles, but I am not sure of OP's risk tolerance.

All those miles you have accumulated, you thought you could get a free flight...ha...this is how airlines make their miles (nearly) useless.