Another thought: Once I get the figure opened up, I may try to find a way to cleanly detach the front fenders (likely leaving the front wheels attached to the arms for stability) and cement them to his back with the rest of the front clip. The only serious drawback to the concept above (I think) is the bulky shoulders, which clearly suggest Magnus even when repainted. Pushing that mass to the back and leaving the upper arms thinner would be more in line with G1 Huffer, who carried a sizable backpack anyway.
One additional plus to this design, in my opinion, is that I don't have to paint ball joints. I'm new to customizing, so I have to keep it simple.
If this works out, I have ideas for TFP Trailbreaker, Brawn, Mirage, Bluestreak, and Windcharger. My boys are enjoying the concepts because they love Transformers Prime, and I enjoy the art.