I have been playing with a breakdown of armor that is not straight 1/3rds, but not 3/6, 2/6, 1/6 breakdown. It is in between and uses 6/15th (round up), 5/15ths(round), and 4/15ths(round down) as the fractions. if armor total # is 1 smaller than it should be, add 1 to first armor section; and if armor total # is 1 larger than it should be, subtract 1 from the last armor section. This gets you a table that is close to the original, yet gives you a hint that those boxes are something other than Hull for those who want their armor to have at least some flavor. The table looks like ...
Total Front Middle Rear
Armor 1/3rd 1/3rd 1/3rd
1 1 0 0
2 1 1 0
3 1 1 1
4 2 1 1
5 2 2 1
6 2 2 2
7 3 2 2
8 3 3 2
9 4 3 2
10 4 3 3
11 4 4 3
12 5 4 3
13 6 4 3
14 6 5 3
15 6 5 4
16 7 5 4
17 7 6 4
18 7 6 5
19 8 6 5
20 8 7 5
21 8 7 6
22 9 7 6
23 9 8 6
24 10 8 6
25 10 8 7
26 10 9 7
27 11 9 7
28 12 9 7
29 12 10 7
30 12 10 8
31 13 10 8
32 13 11 8
33 13 11 9
34 14 11 9
35 14 12 9
36 14 12 10
37 15 12 10
38 15 13 10
39 16 13 10
40 16 13 11
Because the slope from 1st section to last section is not as pronounced, I think that very little if any cost increase should accrue with the caveat that you can never have more armor than hull unless you want to pay an extra surcharge for it.