wing nut

Here’s a topic you don’t see every day…
My sail bag is 4 sqm of windage. I want to minimize it when the sail is down and improve performance when its up……… 🙂 and save money – Quoted $2500 for a new sail bag. Don’t want to buy a new boom, just want to fabricate some attaching wings to the existing boom.
My thoughts are to make a low profile, wide bed for the sail when down and have no sail bag, just a removable flat cover. At the same time shape it to create a winglet to reduce the air spilling under the sail hopefully to improve efficiency. See pic below
When down the back end should hide the sail in the silhouette of the boom but the forward end will sit well up above.
Any feed back would be appreciated. Read on.