There's really no fat to trim here. You have the leading edge, trailing edge, spar and sheeting. You can't compromise any of them by eliminating them. The booms can be flat sanded and tapered as well as the elevator but truth be told, they really need all the strength offered. I have built several of them and never weighed one of them nor did I ever have an issue with a Black Widow flying one. All of mine have had Black Widow engines aside from the current one I have with a Tee Dee. If your engine isn't up to the job, I would be seriously looking into it. As Bill mentions, 25% nitro and a small prop like the 5x3.