if you add just a bit of fuel to your AMM designs, they can fly as far as your regular combat missiles (my opinion is that you should keep these missile classes separate though, and, tech level permitting, you should increase warhead yield a bit) and you can launch a lot more of them per minute then big missiles (because small launchers are both smaller (duh) and reload faster) in addition to presenting more targets for interception, this decreasing the effect of enemy CIWS.
let's examine 2 designs of equal tech level:
Hammerer 06-33-15
Missile Size: 6 MSP (0.3 HS) Warhead: 15 Armour: 0 Manoeuvre Rating: 11
Speed: 33300 km/s Endurance: 21 minutes Range: 41.2m km
Cost Per Missile: 7.1083
Chance to Hit: 1k km/s 366.3% 3k km/s 121% 5k km/s 73.3% 10k km/s 36.6%
Materials Required: 3.75x Tritanium 3.1593x Gallicite Fuel x2405
fires 1 time per minute (60 seconds), so with 6 units of space available it will do 0.25 DPS
Piranha II LRM
Missile Size: 1 MSP (0.05 HS) Warhead: 2 Armour: 0 Manoeuvre Rating: 11
Speed: 32800 km/s Endurance: 33 minutes Range: 64.4m km
Cost Per Missile: 1.0711
Chance to Hit: 1k km/s 360.8% 3k km/s 110% 5k km/s 72.2% 10k km/s 36.1%
Materials Required: 0.5x Tritanium 0.3101x Gallicite Fuel x625
Development Cost for Project: 107RP
fires 1 time per 10 seconds, has a 0.2 DPS on it's own and you can fit 6 launchers into 6 spaces for 1.2 DPS. And it goes further (though it does hit marginally less often).
if you trade a few tubes for magazines, you'll easily be able to afford sandpapering the armor off your enemy before wreaking havoc on it's unprotected insides.