Last time I flew into BOS, my 747 flight was delayed and arrived together with another 747. Both were sell-out flights, so that pretty much equals an A380. The whole lot was processed through 3 of the 14 possible positions for non-US citizens. Not sure what the situation in LAX is, but in BOS, there should be no infrastructure problem. EWR processed a similar situation in no time flat with all positions staffed last September.