You probably could, but really I think the added weight actually benefits the plane when it speeds up. Because your elevator control is based on throttle, and not flaps, if it's too light it just takes off vertically. That's why I added weight to mine, because with the speed 4 motors gives you, you get a lot more lift--too much really to keep it near the ground an in range easily.

I'd encourage you to give it a shot and see how it works though. You could always add more weight anyway later if it's not enough. Reversing the motors will introduce some complications though I imagine