You could build a NAT LOFT. You could time compress a crossing down to an hour and a half from logging on with Moncton to coasting in with Shannon. Wouldn't even need a full motion sim. I've seen a CPDLC training system where an instructor played ATC and students clicked on a computer screen CDU. The instructor can play ATC to several training stations at once. Have another instructor moving up and down the line to explain as necessary. Pair up students, start a flight every 30 minutes and you could push through a class of 30 in a day.

Not sure when Atlas changed from doing a NAT crossing in OE to just doing an oceanic leg.