Re: Maximizing efficiency under sail
If light airs are expected on that route you would see significant gains from an Asymmetrical lighter weight sail vs your large genoa. A true Asymm will probably be usable between 60 deg to 150 degrees apparent to good effect. Since you're doing a 'circle route' of sorts it seems to me that barring heavy tradewinds you'll get good use out of such a sail.
Setting up a conventional symmetrical spinnaker is hands down the better way to get downwind, but unless you've all the required gear already that's a lot to put together, and on a 45 footer it can take a few bodies to safely and effectively gybe the sail.
If you've got a decent 'white sail' inventory then adding a carefully selected Asymm would be my choice for an overall effective versatile sail. Unless I'm mistaken the so-called Code 0 sails are mainly light weight headsails for closer-to-the wind-work (similar to what we used to call drifters).
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)