I don't think the rotation pattern is all that important. None of the tires drive or steer the trailer. I do rotate my TT tires once a year for the same reasons others have posted about the uneven weight they carry and also tire flexing and scuffing differences of tandem axils while making tight turns.
Maybe it makes no difference, but all I can say is in 19 years, thousands of miles of travel, and three sets of ST trailer tires I have not had a single blowout.
Dave has it right, "However you have do what makes you comfortable."