oldturtle, what do you have in the offset position?
To the OP, there are many 45 degree offset rails, and offset to the barrel should be better than offset to the scope. Mounting the sight off the handguard or flattop still puts it over the bore, and therefore is the same as your scope. Mounting 45 degrees of the scope makes the scope the bore, and it is 1.5" from the bore. Something to think about, although in real life, it may not make that much of a difference.