Generally.. If I am leaving the jib off I am looking to do it to dramatically depower the boat.
This means you only need enough rig tension to sheet in relativity tight going block to block with the main sheet.. More rig tension generally means more power...
You could use a cable from the jib and rig it just like normal without the sail up.. This would be the best if this is something you are planning to do quite a bit IMO... and want to be able to adjust rig tension.
I would just mount the forestay down lower.. You could use the Jib Halyard.. Tie off to a length of rope tied to your mast stand.. Just like many do when stepping the mast solo. This will allow you to put significant tension on the rig so you can hook up the forestay just as low and tight as possible... Or freely take your pick.... But remember you only want enough rig tension to be able to sheet all the way in just as you are going block to block to depower the boat as much as possible...
Just look at how the non 'turbo' H14 is rigged.... And nobody gets real excited about lots of rig tension on those that I am aware of...
What I have done... I just take the jib sheet and run it to the chain plate and then use the Jib sheet to tension the rig...
Like this..