You can do that mix if your radio has programmable mixes. I do the same thing on my Slinger wing so that when I back off the throttle the elevator is at the right trim for power off glide. I doubt it would take much at all to correct it. Start about 2% down at full throttle. If your radio is easy to adjust while flying, take off while at the % setting that needs tuned in. Get up to altitude and set elevator trim at low throttle then got to full throttle with the mix on and start adjusting till it flies level. You may still need to fine tune it but that will get it pretty close real quick.
Matt