[Suicide Junkie]

I think a thickness mount for armor will be good too:
EG:
Steel Armor Plating I
size - 1
HP - 3

Then we have mounts:
1-inch plating: size x1, hp x10
2-inch plating: size x2, hp x18
3-inch plating: size x3, hp x24
4-inch plating: size x4, hp x32

The rationale being as follows:
Thicker plating is less efficient in hp/kt, however the large hp per component makes it less leaky, and also improves the performance of any leaky shields which are still operating.

For example, the 1-inch steel plating (when shields are not destroyed) will be immune to weapons of less than 30 damage per hit.
4-inch plating, on the other hand, will have 80% the structural strength of the thin armor, but will be immune to weapons of less than 96 damage.