Thanks for all the input. Bob's post answers the original question best, and the other posts are very valuable as well. I may just build myself a long neck and put the fifth string nut at the fifth fret--it just seems it would give more flexibility in tuning it as well as less worries about string tension or lack thereof. I've got a low voice so if I want to play and sing in the same octave a standard banjo doesn't do it for me.