John;
Hi! I'm going to guess that you are likely right - remembering that this is a hypothetical paper panzer - those look like they could be vents / covers for fume-extractor fans positioned above the gun breech. In which case, the outer ring would be a welded-on bullet & splinter deflector, like those little "walls" seen around tank hatches, and the inner disc would be the fan cover mounted up on posts or something like as spacers.
IF all this is the case, there should be no gap between the hull surface and those outer splinter-barrier rings, but there would be some around the edge of that inner plate or disc. Having said this, maybe it would be appropriate for a couple of holes to be drilled thru those outer rings at hull-top level and on the lowest side, as drains to run rain-water off. Sort of like those seen on other tanks with various fittings around things.
Least ways, this is my opine!
Cheers!
Bob