I have, in the past, used 1/8" sheet lead and made a strip that would go under the engine and span the motor mounts. I used long screws for the two front mount screws and dirlled the lead to fit over these extended screws. A washer and a nut with a liberal amount of thread lock, and you have an ounce or two out front where it does the best.

On my Rupert's Dad, I found I needed about 8 oz in this mannor to balance the plane. That was with a Mag 52 four stroke. Then I found that replacing the 52 with a Mag 70 four stroke would account for 7 of those oz, and I could put the weight to work. I had to mill about 2.5 MM off the inside of the motor mounts so I could use the same bolt patern through the fire will. It has worked very nicely. I solo-ed it today. I flew it a couple times with the buddy box some months back and I thought it was very intimidating. Today it was a blast.

On my first 4*60, I needed six oz and there I used 1/2" square steel stock and cut two pices the length of back of the motor mount and then dirlled them to fit the motor mount screws pattern. It was a clean addition of weight and it also saved a bit as the motor was extended by 1/2"

If you can't take care of the weight issue by moving batterys, put weight up front that you can use if possible. Say an OS 46

Don