Let me add an idea in the spirit of your post. They could ship in these things on both sides of the border and just dump the stuff over both directions.
Problem solved.
“How would a driver get it the few feet across the border without entering the foreign country?”
Push it. Seriously. Rig up a bulldozer with some big rubber pads and push the trailer the last 20 feet across the border.
Of course only after hosing down the trailer down with 409 and bleach to kill any little covids that might be on the hook ups and back door.
Hmm. I wonder if they make the trailer sit for 24 hours or whatever they say it takes for covid to “die” before they unload it?
I saw a flaw in my plan, but I think I solved it. Truck lifts.
https://www.youtube.com/watch?v=PenhM3mYhGk
Logistics
Have a third driver that only does the crossing part. Say, start the first dropped off truck Canada to Us, cross border, dropping truck getting second to go North TO Canada,, dropoff Canada side, next truck south to US , cross, drop off. Could be ten miles in either side. But the key is logistics of having a Crossings Only driver. He can show up at first spot in his pickup truck, work eight to ten hours, end up at start, and drive home. Only crossing border all day.