"use a civilian Catamaran "
I had the **** taken out of me when I suggested that a year or so ago
I'm not sure if there are any Argentinian registered large high-speed ferries, but theres joint Argentine / Uruguayan company with a Uruguayan registered fleet on the River Plate which includes one of the larger Incat cats, plus a sister to the Superseacat high speed monohulls.
They'll each take 500 people plus 50 cars, and there are a number of smaller passenger-only cats capable of carrying ~300 people.
If the Argentines were to use those (they'd need reasonable weather) and launch from Rio Gallegos (the nearest military port) they'd only need a few hours transit.
Think about it. Airborne commando force to knock out the aircraft at MPA, then a landing by marines from the high speed ferries, followed up a few hours later by troops and tanks on conventional RORO ships
And if you're wondering about loading ramps - they could use something like a mexeflote, or even tow in a floating linkspan