Until recently, I played the same club setup you have. I loved the lower level G20's. Then the tees moved back...
When I've played alt-shot and another player had the L69 Rocketballz driver, I was amazed at the distance they got, especially in heavy wind. Caveat: I did find that players tend to spray the ball around, however. More missed fairways than I find acceptable.
The L81 G20 is easy to ding/near-ding and quite foregiving of off-ding hits. I find it easily provides me an extra 10-30 yards compared to the L59 G20 driver when playing a decent ball. All depends on wind conditions, course, and how I use spin. Still experimenting and learning.
It's a bit of a slog to L81 for you, and many, many months until you reach L90. I can understand why you're looking for any extra distance you can muster given you're playing from Legend tees. Obviously, if you have the credits to spare, rent the L69 Rocketballz and give it a good workout. Good luck to you.
Rich