Hi there,
This is Bogdan from Romania.
I'm a mechanical engineer - specialized in the industrial robotic field, 3D designer and modeler (from time to time and some projects I could make the functional prototype too).
I'm doing product design, industrial design, reverse engineering, ideation, etc.
I have over 15 years experience working on various systems/devices across multiple industries, from concept to launch.
1 - in order to use replaceable hinges, the mounting panels need to be redesigned too
2 - from the pics shown, it looks like the hinges are undersized, so consequently, they will eventually break... (could be also an issue with the alignments of their axis)
3 - it is possible, but not advisable to have the real army vehicle scaled down and to keep the same proportions for certain functional elements (these elements could become very thin and friable)
4 - if you have a 3d file for the model will be easier to make the modifications... (based only on the pics and measurements will may not have an accurate output)
For any more questions we could chat here.
Regards
Bogdan