I can't see such a fleet engaging in a stand up fight with military vessels if they had any option. They would use trickery and cunning to apply overwhelming force wherever possible.
key points:
Converted civlian ships - base standard weaker/more fragile than military equivalents - better ships get expensive.
Eclectic: possibly build-a-hull similiarly to tyranids
eg:
Maquis Light Raider, 10pts
Escort 1
Shields 1
Speed20
Turns 90
Armour 4+
Turrets 0
Prow WBs 30cm F/L/R FP3
May take:
Extra speed for 5pts per 5cm of speed up to a max of 40cm total.
Extra turrets for 5pts per turret to a maximum of 3
Armour 5+ all round for +5pts and/or armour6+ in any facing for 5pts per facing (sides count as two facings).
S1 15cm F/L/R Lance instead of Prow WBs
S2 F Torpedoes instead of Prow WBs
FP3 30cm F/L/R Ionic Blaster instead of Prow WBs for +5pts*
Maquis Heavy Raider 20pts:
Escort 2
Shields 1
Speed 15
Turns 45
Armour 4+
Turrets 1
Prow WBs FP3 30cm F/L/R
Dorsal WBs FP3 30cm F/L/R
May take:
Extra speed for 5pts per 5cm of speed up to a max of 30cm total.
Extra Shield for 5pts.
Extra turrets for 5pts per turret to a maximum of 4
90' Turns for 5pts
Armour 5+ all round for +5pts and/or armour6+ in any facing for 5pts per facing (sides count as two facings).
S1 Lance 15cm F/L/R instead of Prow WBs and/or Dorsal WBs
S2 Torpedoes F instead of Prow WBs and/or Dorsal WBs
FP3 Ionic Blaster 30cm F/L/R instead of Prow WBs and/or Dorsal WBs for +5pts per hardpoint.
S1 Fighter Bay instead of Prow and/or Dorsal WBs for +5pts per hardpoint.
S1 Bomber Bay instead of Dorsal WBs for +5pts.
S1 Assault Boat Bay instead of Dorsal WBs for +5pts.
S3 Bombardment Cannon instead of Dorsal WBs for +5pts.
Maquis Liberator Class Cruiser
60pts
Cruiser 4
Shields 1
Speed 15
Turns 45
Armour 5+/4+
Turrets1
Prow WBs FP3 30cm F/L/R
Dorsal WBs FP3 30cm F/L/R
Port WBs FP3 30cm F/R
Starboard WBs FP3 F/L
May Take:
Armour 5+ all round for +10pts and/or Armour 6+ for +10pts per facing (sides count as 2)
Additional shield for +15pts
90’ Turns for +15pts
Additional Turrets for +5pts each to maximum of 4
Additional Speed at +5pts per additional 5cm to maximum of 35
Upgrade all direct fire weapons to 45cm for +20pts.
+D6 AAF for 5pts.
All Hardpoints:
Replace WBs with S1 Lance
Replace WVs with S2 F Torps
Replace WBs with FP3 Ionic Blaster for +5pts
Replace WBs with S1 Fighter Bay for +5pts
Prow/Dorsal hardpoints:
Replace WBs with S3 Bombardment Cannon for +5pts
Replace WBs with S1 Bomber Bay for +5pts
Replace WBs with S1 Assault Boat Bay for +5pts
Fleet special rules: Maquis have a -1 modifier to ld Rolls to navigate terrain or disengage. *The Ionic Blaster uses the gunnery chart as normal, but always hits on a 4+. If all the target's shields are down, the Ionic Blaster does not cause a hit but rolls 1D6 on the Critical hits chart isntead.