This situation specifically applies to the Ares and Posiedon superheavy mechs since they are tripods, although if all Large(LG) mechs are based on round bases then it would also apply to the Omega and Orca mechs.
The Large (LG, p.86) Special states that the unit covers a 2" AoE template area. Does this mean a unit with this special is mounted on a circular base with a 2" diameter instead of a hex base or does it use a 2" hex base? Likewise with a Very Large (VLG, p.91) and Super Large (SLG, p.90) miniature, which say they have 4" and 6"+ diameter areas respectively, what type of base are these mounted on?
The rules for Large units on p.64 make no mention of special firing arcs for these units, nor are there any diagrams on p. 65.
The rules for standard firing arcs on p. 41 have an entry for Three-Legged (Tripod) Mechs which states they may still be attacked from the rear as a normal mech.
The Attack Direction rules on p. 48 only reference hex-based miniatures. How do you determine if you are attacking a round-based miniature in the rear?