There was an option to get an expert system for a balance tail in SR3 somewhere, which basically made it worthless for balance as long as the expert system was active and useable as a kind of tentacle with a +2 to target number for any task where it is used . .
Now combine this with the penile implant . .
If you DO go with a normal cyber-eye, which takes up essence rather than capacity, do NOT forget that you get to pimp out that eye with all kinds of stuff again, without these addons taking up essence. And since the tail has no capacity rating, you can only take a normal cyber-eye anyway . .