I know several players who use the Reagan 5th String Removeable Capo available from Janet Davis Music. This just slips over your fifth string and sits right on any particular fret. You tighten the screw to lock it in place or remove it and put it in your pocket when not wanted.

Banjo players are, to a man, well known as gadget freaks. I get to play with some world class banjo players and they've tried every 5th string capo known to man. Most of them have now abandoned 5th string capos entirely in favor of spikes.

Have the spikes installed at the shop that does your repairs and setups. The shop where I occasionally work charges $3.00 (USD) per spike. We take great pains to protect the instrument, get them all lined up properly, and make sure the clearance is correct for the strings you use. If you expect to play any bluegrass style banjo, get pegs installed at 2, 3, 4 & 5 since you'll need those for all the keys you'll be using. If you're certain you'll only be playing old-timey music, you can get by with pegs at 2 and 4 (add one at 3 if you play in F using a D tuning).

      - Mark