The Rotterdam/Galicia/Bay LPDs from Royal Scheldt operate with crews of 60-180.
http://www.naval-technology.com/projects/rotterdam/
http://www.naval-technology.com/projects/galicia/
http://www.naval-technology.com/projects/bay_class/
60 on the Bays with no Weapons or Defensive Sensors.
~120 on the Rotterdam and Galicias with a Defensive Suite
~180 on the Galicia with an Amphib C&C Suite
As all the vessels can carry up to 700 troops, or be enlarged a larger C&C capability can be provided.
I don't really understand why 1 or 2 bare cans couldn't be provided as floating warehouses to be manned with Reservists when they need to move. Forget about thinking of these things as combat vessels. Rely on the escort vessels for defence beyond a limited point defence capability.
Let's just see about getting places first, and perhaps operating in our own and other benign environments before we consider joining the USMC storming beaches.
As to the issue of one trick ponies, perhaps the Danes can show us a thing or two there with their 6000 ton Absalon Class Command and Support Ships
http://www.navalhistory.dk/English/TheShips/Classes/Absalon_Class(2004).htm
and the derivative Patrol Ships.
http://www.navalhistory.dk/English/NavyNews/2006/0622_PatrolShips.htm
They are essentially Frigates with a troop carrying capacity of 69 and a pair of 40 knot LCVPs as well as a RoRo deck (I don't know if it has a floodable well).
They are well armed (equivalent to the CPFs and the DDHs).
Just for grins the Danes also have these new 1700 ton Arctic Patrol Vessels you are likely to meet up around Hans Island.
http://www.navalhistory.dk/English/NavyNews/2006/1120_NewOffShorePat.htm
The Air Force got behind the idea of moving guys in green around the world. What will it take to ease the mind of those that IHS is talking to that seem to have a problem with "launching soldiers". Does it help if they think of soldiers as "smart missiles in green"? ;D And no wisecracks about the intelligence levels. >