I would definitely go with a tailpiece and adjustable bridge of some sort. A pin-type bridge would just be asking for trouble, both from structural and intonational standpoints. The intonation problems inherent in 12-string guitars will probably be compounded on an 8-string bass.


(Wrinkles doubtlessly needs no explanation of the "12-string intonation problem", but just in case there's a casual reader or two out there... A thicker a guitar string needs to be a little longer than its thinner neighbor for proper intonation. That's why guitar saddles are slanted. When two strings of very different thicknesses are used in a course and they are the same length, they will get progressively out of tune with each other as you go up the neck. The only solution is to adjust the length of each string individually.)