Flihi pro, u505, all of these driving irons play pretty similarly at this point.
I had the a similar dilemma as you.
I took out a conventional 3 wood for a mini driver so that one club that was in between 3w and 4i had to cover a lot of ground.
My home course is firm and windy as well so I wanted to make sure that it would be a club that could cut through wind if necessary.
So I built a fairway wood with 5 wood loft, at 7w length. Went with a low spin 5 wood head, stealth plus, and play it with two shaft. A low spin ahina shaft at 42" or higher spinning shaft at 41.5, depending on course I'm playing.
The reason I went this direction instead of UW is fixed hosel, with an adjustable head, I can tweak this club from 17 - 21 degrees of loft, and varying length to fit whatever need I will need for the day.
Low spin head with low spin shaft will keep my ballflight super flat on days I need it that way, or going 20 degrees loft with soft tip shaft lets me play it more like a hybrid.