I suggest the LVT 2 with one .50cal and 1 .30cal. It could only hall 7 passengers and 2 crew but we could say we had 3 guys skiing behind or something and call it good. Then the LVT(A) 1 as the second version (like M3 and M16) with the M3 light tank turret and 37mm gun plus rear firing .30 call for landing support. We could get crazy and have for the second version the LVT(A) 4 with the 75mm short howitzer! Cool

I would suggest the DUKW but it's not as well armored. But there were MANY versions of them including some with 25-pdr field guns and some with 4.5in rockets. The LVT 3 would be good also but it came out in the last year of the war so not quite as common as the LVT 2's.
BTW there are still DUKW's out there in service in a few Western armed forces. The Brits used them into the 70's. Oh, and the Israel army still uses the M3! I seen one on the news a few months back. LOL still some old WWII equipment being used out there, A good design never dies it just fades away. Like the DC-3 (C-47). There's still a lot of them out there flying.
Would love to hear some other landing craft suggestion from you all.
C U up there,
Jimdandy