Is this the one being built in the west end of Edmonton? I don't really have too much insight other than to say that you are probably solidly into alternative solution territory, especially if they are stacking the containers on top of each other.
FM DS 3-26 classifies 'Manufacturing/Assembly of Boats, Highway Trailers, Trucks, Boxcars, Mobile Homes or similar' as an HC-3 occupancy, with a density of 0.5/3000 for a ceiling height of 45-60 ft. But that is 'manufacturing', not storage.
Maybe ask if a similar UHaul warehouse has been constructed recently, and see if you can get a hold of the sprinkler plans to have a look.
Also - there has got to be some insurance company involvement in a job like this. I would reach out to them as well.