I think there are a few things that make it look "odd."
#1 - the transition from cab to sleeper is very forced - and that is both on the sides and the top. A softer, more gradual affect may help. That could be done with something as simple as fiberglass or sheet metal making it a more gradual change.
#2 - the color shift from red, to black, back to red - obviously easily fixed with a paint job upon completion.
#3 - the line along the bottom of the truck is not consistent so it makes it look like it was not meant to go together. I somehow want a more solid line as it transitions from the cab to the sleeper along the bottom as well. I would continue this beyond the cab if you were going with a truck bed or even with something in front of the duals if a flatbed - whether that be storage boxes, etc. I agree a flatbed may be better, but that is my opinion.
I still applaud you for trying this out...I wish I had the resources (time, energy, tools, knowledge, location, etc.) to take on such a project.
