Lots of time experimenting (as you note) will provide best results, but I don't see why the typical stereo configurations mentioned on this site would not work well from about any distance from a foot to ten feet from the harp. You may experiment with raising/lowering the pair and in/out from distance.
I would think (personally) that splitting the mics on the string location would not work well in playback. I would suggest trying to get the full range of the instrument in both mics, by stereo micing from a chosen distance.