5 string baritone uke conversion

Hi all I'm new to the site but not to ukes. I've been playing for twenty odd years.
I recently bought a cheap baritone uke and after changing the top nut, lowering the action and putting decent strings on I find it's quite a cool instrument although it lacks projection.
I also play 5string banjo which is loud and I don't like the tone when muted. So I've tuned the bari' to open G (DGBD) and can play most banjo stuff on it plus many other styles. I'm thinking of adding a 5th string to practice more involved banjo stuff quietly. I apologise if this is an athema to some. I was wondering if anyone else has tried this and if so, how they did it?
Cheers

Never tried it myself, but Uncle Dave made one: http://www.youtube.com/watch?v=Pc3J63f09ks

Hi and thanks for the link. Unfortunately it wouldn't work for me as I want to be able to tune the extra (5th) string independantly and situated on the left side of the neck.
cheers