You don’t necessarily need superheavy vehicle rules to replicate these kinds of real-world choppers. The H-21 only weighed 4 tons empty and had a max takeoff mass of about 7 tons. Even the world’s largest chopper, the Mi-26, weighs 28 tons and has a max takeoff mass of 56 tons.
But if you want to do considerably better than the Karnov or carry the Mi-26’s payload internally, then you do have to resort to the superheavy rules.
Since you don’t care about combat worthiness, the support vehicle rules offer even more efficiency.
Or just borrow the canon Trireme and St. Christopher, as suggested above.