or one could simply break the vehicle in 3 part, instead of 50/50.
I'm not sure if this would actually improve the game meaningfully. Unless other changes are made, you'll still have cases where shots taken from the "front" of the vehicle could strike the side armour, even at absolutely extreme angles that simply don't make sense (I.e; A shell striking the side armour at 179 degrees), and having a third zone type would arguably make the whole "armour" system more inconsistent, as you're even more likely to strike an "unintended" armour zone.
If the engine makes it possible; A rather crude "solution" would be to compare the position of the attacking unit to that of the vehicle being struck. If, for example, the AT unit were in a 90 degree cone in front of the tank, any hit (regardless of where on the model it actually strikes) would be a "Front armour" strike. So forth and so on for "Side" or "Rear" armour.
I've made a crude mockup to try and help visualising what I mean. Units located in the light green section would always strike "Front" armour, purple section units would always strike "Side" armour, and orange section units would always strike "rear" armour. (The grey box obviously representing a vehicle, and the dark green, yellow, and red lines representing the various armour zones)