not knowing much about pick ups i would suggest trying slanting a guitar pickup accross the strings, or maybe have a look for a company that makes pickups and see if they can make u a 5 pole pick up, or u could look at making ur own five pole pickup im not sure if that would work tho not knowing exactly how pick ups work, erm, as far as i know simply a guitar pickups end pole peice hang over should work, maybe you could try three mini humbuckers running in line with the strings and have an entire coil per string and tap each coil off seperatly (just an idea i dont know if it would work, i cant see why it wouldnt) this would still leave half a pickup hanging over but i think it could be left disconnected, this may be more suitable if the strings are close together
you could try finding or making 5 single pole pickups then u could position each where ever you wanted
another option instead of pickups might be a microphone
anyway hope that helped a bit maybe it didnt, somebody more experianced n intelligent than me should be able to offer some more accurate information