A worthy contest! Legionic could you post the top 3 ships of each week in your OP or another thread? I would really like to see the winners!
Though the part requirements seem overly complicated and the weapons have very different power and crew requirements.
I think the easiest way would be to make it a money limitation. You could make several brackets for people with different time constraints:
Cruiser (Default, ~250k credits)
Battleship (Intermidiate, ~550k credits)
Dreadnought (Champion, 1200k or even 3000k credits)
This way you donยดt have to count the parts as you see the total worth of your craft with one look.
World Limiting tonnage would penalise using armor unduly in your proposal as itยดs three times as heavy.