Hi Andy,
Welcome to the RS Aero fleet!
With the sail hoisted the primaries should just go slack when the control line is fully released. Move the bowlines small amounts to achieve this. That way you should not run out of vang/kicker range when fully pulled on, whist also being able to ease enough for those light wind runs too.
Note that the boom is a little higher on the 5 rig, but if you get it 'just slack' for that you can have enough range for all three rigs.