>No E-series vehicle was ever built, nor even completely
>blueprinted, before the whole effort was abandoned in favor of
>emergency production of existing designs.

Welllll, yes and no. It's a debate on whether or not a partially-built E-100 chassis qualifies as "built." But that's a bit like arguing that the H-class battleship existed because the Kriegsmarine managed to put down some steel for the keels before the whole thing was put on hold for resumption "after the war."

>As such, E-series vehicles do not meet the IAF's rule that vehicles
>fielded by Armorsport teams be faithful reproductions of ones that
>were realized during the war (a requirement that the Maus barely
>satisfies, since a whole one and a half prototypes were built before
>the project was abandoned).

Then they must love BC Freedom, whose heavy tank force in GUP das Finale consists of the ARL 44 which only existed as a wooden mock-up by VE Day. The first prototype didn't even roll out of the factory until June '46.

The GUP approach to rules is in the "more like guidelines" vein, such as Yogurt Academy (aka Bulgaria) who quietly managed to acquire heavier tanks to make their school competitive, but did so in a way that makes it look like they looted a junkyard and welded together whatever they could find into functioning tanks. Then there's Continuation Academy (aka Those Whacky Finns) who like to "borrow" tanks from Pravda and Kuromorimine.