Just did the same.
Noisy large museum hall, stone everywhere, walking people, small concert of a young player, bit nervous
Theorbo, which is a larger lute, body a bit bigger than a lute's body, but an octave of bass strings added - more than 1.5m long.
If someone would like the result I used two omni mics around 25cm from eachother, lenght of the body of the instrument away from it, "pointed" asduring the acoustical guitar recording - on the 12th fret
Enjoy!