The general gist of it is not to make Corvettes viable or anything (although this might come in handy during WW3 if this gets implemented, but I digress 
), but rather to give new players very basic ideas on fitting and the themes of the 4 Empire faction ships.
Without specifics, I think every “civilian” fit (that is given to you when you “board your corvette” in a station) should include as much modules that the respective Corvette is bonused to as possible, while still maintaining a resemblance to a “normal” fit that one would actually use.
If you want to be more specific, I have ideas for each of the 4 Corvettes. First of all, I think the Caldari and Minmatar corvettes should get a 3rd Mid slot, while Amarr and Gallente ones should get a 3rd low. Then, assuming this, here are the fits (I used T1 modules where civilian variants don’t exist or are unavailable from the fitting window module list, but I assume those to also be civilian, with respectively downgraded stats):
[Impairor, Civilian Impairor]
100mm Steel Plates I
Multispectrum Energized Membrane I
Civilian Damage Control
1MN Civilian Afterburner
Tracking Disruptor I
Dual Light Beam Laser I
Civilian Miner
Acolyte I x1
[Ibis, Civilian Ibis]
Power Diagnostic System I
Civilian Damage Control
1MN Civilian Afterburner
Multispectral ECM I
Small Shield Extender I
Light Missile Launcher I
Civilian Miner
Hornet I x1
[Velator, Civilian Velator]
Civilian Armor Repairer
Multispectrum Energized Membrane I
Civilian Damage Control
1MN Civilian Afterburner
Remote Sensor Dampener I
125mm Railgun I
Civilian Miner
Civilian Mining Drone x1
Hobgoblin I x1
[Reaper, Civilian Reaper]
Nanofiber Internal Structure I
Civilian Damage Control
1MN Civilian Afterburner
Target Painter I
Civilian Shield Booster
125mm Gatling AutoCannon I
Civilian Miner
Warrior I x1
As a side note, I think at some point players should be able to “board” any of the 4 Corvettes, not just be locked to their respective faction.