[Imp]

I have not had a chance to play it yet but your answer is a good one, perhaps you should state something similar in the campaign text.
My gut feeling is if you adjusted it the best suggestions are a few more rocket launching barges & perhaps the DD tanks a bit early.
This would give you more tactical options where as cannon fidder promotes bad play.
Most campaigns seem to be pitched to easily your core taking few losses, less than in most regular battles so people expect the majority of their core to survive. The ANZAC campaign (I think) was the exeption very hard in places with the odd easier one that let you rebuild.