Hi Louis!
First of all yes, this will be a gunboat 109. After several nights thinking about what to build and after sweeping my entire decal stash there was only one plane that fit the bill of matching the factor of having 2 engine cowlings, wich meant 2 identical squadron markings, plus being enough interesting for me to build it (this particular plane I never saw in a model or in a decal sheet).
The give away about future versions is exactly what you point out, several inspection panels and hatches are in need to be filled in, as per instructions call out. Reminds me the Hasegawa way :-).
About the minor issues of sink marks, not all are located where they became hidden during assembly. At least a couple of these remain visible in the cockpit and several in the radiators parts.
That said, it is NOT my purpose to trash this kit, au contraire. It is a ingenious model, with some better than most detailed areas and it builds like one expects from Tamiya, but one also cannot forget the price tag just to find such nagging issues that could be easily avoided in my opinion.