I would encourage you to balance out the sides as much a possible.
Well that's one way to do it.
Not all boots are created equal, Some boots mfgs make their boots conform more to the leg, other don't. The boots should collapse inside the shin regardless.
Regarding the back piece, I talk about this issue in that section of the assembly. Due to how Anovos shaped the top sections it effects how the armor sections come together. You may have to make alterations, also discussed in that section.
Hope this helps