Bruce that is the same problem I ran into.... I ended up with a Magnum 80 four cycle before the CG was right... I flew mine with an OS FX46 and it was awful. You could fly it with the cg way back and tail heavy but it's inverted flight was half stick down to keep it level..

I went through the same things as you I moved every thing I could to the hatch with the fuel tank and still couldn't get close...

You can read some of my messages a little earlier in this forum about this...

The plane fly’s great now that I have an 80 on it... It is way to much engine but it was either that or add like 3 ounces of weight to it... AND I don't like adding weight I would rather add power...

These planes are nice but the radio layout for the CG is terrible if you ask me...

And the cg is right at 4" with the 80 it was like 5 1/2 with a FX 46...