Best option...Lights that actually work, starter that cranks instead of laboring... They build alternators that look like generators if looking stock is important... Distributor won't care....
FWIW an 8 amp 12v draw being fed 6v is actually gonna use 16 amps.... Which probably exceeds the output of your generator...
BTW that relationship between amps/volts is also why the starter will work so much better... Most starters draw 100-140 amps at 12v... Which means it draws 200-280 amps at 6v....