[ShrimpBurrito]

Wow, you're only talking about 1.5 inches of clearance (3.5 cm), so about 3/4" on each side. If that really is the clearance, I would think you would be fine, as the trailer can be strapped to the floor. But I would call the factory, describe your plan, and ask them to take some VERY detailed measurements, emphasizing that fractions of an inch are critical. They may even need to leave off things like marker lights, which are probably about 1/2" thick, as they may not be included in their measurements.

And if they say it will fit, I think I would be inclined to tell them that I would purchase only if they guarantee it will fit. They can get a container brought to the factory for a test fit, or take a trailer to a warehouse to do it there (such as the one where your freight forwarder is located). They may charge you a bit for their time to do it, and rightfully so, but it would be money well spent.

Dave