rigging gaff cutter

[glynn]

I know this is a biggy, but i am about to start rigging my new gaff cutter, and having made all the soft eyes for the top end, I have started wondering about the tension i need to apply to all the standing rigging that attaches to bottlescrews,etc.
Do I need a tension gauge like for a bermudian rig, or can a gaffer really be slacker.

I have looked in Brion's books, Tom Cunliffe and Martin Tregoning, but they aren't specific about tension.