I would double check those state inspection requirements. I am in Virginia and according to the Va State Police, LSV's are not required to get state inspections because they do not go faster than 25 mph. Above 25mph then Federal Safety regulations kick in, airbags, 5 mph bumpers, etc. The officer I spoke with said LSV's would not even pass because of the airbag issue. Not sure on your original tax credit question but as you have found there is not a lot of info out there.
Regulatory specifications
[edit] United States
On 11 July 1984, the U.S. government amended Federal Motor Vehicle Safety Standard 208 (FMVSS 20
to require cars produced after 1 April 1989 to be equipped with a passive restraint for the driver. An airbag or an automatic seat belt would meet the requirements of the standard. Airbag introduction was stimulated by the U.S. National Highway Traffic Safety Administration.[32] However, airbags were not mandatory on light trucks until 1997.[33]
In 1998, FMVSS 208 was amended to require dual front airbags, and de-powered, or second-generation airbags were also mandated. This was due to the injuries caused by first-generation airbags, though FMVSS 208 continues to require that bags be engineered and calibrated to be able to "save" the life of an unbelted 50th-percentile size and weight "male" crash test dummy.