- drop 1 RDU (3000km radius)
- wait till it builds airstrip ~ offensive airport (takes 12 hours?)
- drop several SF units and "paint" the country map while waiting for the airstrip to be build. this should take the WI down to 30 or so
- when airstrip is build, drop 1 LRD on it. popular combo is 2600/1000 HA/HT
- kill defending air force, popular combo is 1000/1000 Drones/FP
- use the LRD to destroy Counties and Towns (no garrison - no casualties), then perhaps Capital, Cities, or optionally State corps.
indeed, in theory, not killing population seems beneficial in the sense you mentioned SimCEO, however, its the easiest, fastest and cheapest way how to win. the good thing is that as a rule of thumb the lower population the faster (%) growth so higher casualties are replaced quite soon.