What is that big black rectangle next to the tracks?

A base for the model?

There is more plastic in that than there is in the rest of the model.

Looks like Trumpeter is taking the Dragon route - most hatches molded closed, tools and towing cable molded on, and absence of PE. This is almost a quick-build kit! That long gun makes it totally useless for the urban fighting more typical at the end of the war, and places even more weight on an already unreliable final drive. What were the Germans (or Trumpeter!) thinking?? (I'm aware this is a what-if, or imaginary tank).

It's probably based upon World of Tanks rather than historical evidence.

A Tiger II with a 10.5cm gun was one of the conceptual designs Krupp proposed late 1944. This did not materialize for reasons such as: the gun itself was not accepted into service, turret needs to be re-designed, additional loader required. Krupp's proposal however was for an L/68 not L/65.

A base for the model? [/quote] I would think the same.

They have to make the kits simple so the little Chinese girls who do the pre-builds can achieve their generous productivity quotas and not despair. All for the glory of the corporate state of the people's republic of China.