Ranger - Extremely Severe Aerodynamic Unstability

[allagator1]

The Ranger keeps flipping itself over in horizontal flight When I apply even the slightest deviation to either Yaw, Pitch or Roll. The Ranger's CoM and DCoM is also unbalanced and the Ranger's flipping issue will be much more severe as more LH2 is consumed during it's journey to orbit from whatever atmospheric body it landed on. This has been a reoccurring issue for me, and I believe that the Ranger was not thoroughly play tested to ensure this wouldn't happen.

[allagator1]

On top of that even slight modifications to attempt to fix the unstability has proved unsuccessful, such as adding verticle stabilizers and small wings at the back, and I will be unable to add larger wings to the Ranger without compromising it's low drag and high manuverability