The Cold War and REFORGER could have been used for justification if the concept had been taken seriously enough early on, but it wouldn't be the reference "Pelican" design. (Seriously, it was a well known
phenomenon and had been reported, studied and even used in 'practical' applications since the 20s) But the technology and capability would likely have to wait till the mid-80s at least and keep in mind that while the DoD actually found the concept to advanced and non-viable in the 90s (
Aerocon Wing Ship concept) by the early 2000s they had changed their mind. (Even though Boeing was still skeptical about their ability to actually build the design)
3000 troops or 1400 tons freight capacity? That's putting an awful lot of eggs in one very vulnerable basket. Why not simply build more C-5s and C-17s? Conventional transport planes are faster too. Pelicans need runways too. Maybe it would offer some advantage due to its cruise efficiency in ground effect but make it smaller. About 1/3 the size. Spread the eggs out a bit more.
Nope.
A Pelican can carry 17 Abrams. A C5 can carry 2 theoretically, and maybe only 1 in practice. I don't believe a C17 can carry any.
Nope? Who says you only have to carry tanks? And anyway build a smaller Pelican then. About 1/3 size. Or build bigger conventional transports.
Read the article and proposal, that was the 'requirement' to carry a massive amount of payload to a far away destination so you don't HAVE to 'wait' on more conventional transport assets:
"successfully deploying an Army
brigade of 3,000 troops and 8,000 short tons (7,300 t) of equipment within ninety-six hours (4 days) instead of the three to six months (91 to 183 days) it required in the past"
The 3-to-6 months IS with 'more' C-5s and/or C-17s, along with standard shipping and air-freight
In the Pelican's case that worked out to about 8,000 "people", or 17 Tanks, or 52 MRLS's, or about 178 standard ISO containers PER Pelican. It's an actual 'freighter' aircraft
That's what the 'customer' (the DoD) asked them to deliver and they were far from the only design submitted. The more 'conventional' approaches had aircraft about the size of the "Roc" carrying modular payload containers, (but needed a bit more than a dozen of them), fast-cargo ships employing everything from 'hovercraft' to semi-submersible ships and of course a raft of hybrid and "conventional' LTA designs. Pelican checked more of the boxes but Congress balked at the core idea, (that the US military actually NEEDS to move lots of troops and equipment anywhere fast) but more specifically the estimated cost of such a project, (several billion JUST to get to the prototype stage never mind the actual vehicle) and vetoed the funding.
The "problem" of course is there's no real 'other' use for such capacity so you're probably right that a "smaller" version would be better but keep in mind that the studies and requirements were driven by the DoD and not commercial applications. And even a smaller design needs to meet some pretty hefty 'minimum' requirements. (As noted they had to carry MORE than a C-5, FASTER than a ship AND be able to land almost anywhere a 'conventional' aircraft could)
Essentially the only way to meet the OP is to have Congress become convinced the US military really DOES need to be able to deploy quickly anywhere in the world and for Boeing to take on the job which in and of itself isn't guaranteed
How would it handle crossing the Great Plains, inland Australia, and other flat places that aren't the ocean?
Flies over them like any other aircraft. It only used GE over large stretches of water. It had enough lift to clear any mountain range lower then the Himalayas'.
Randy