It isn't rocket science. Refueling stations for natural gas are few and far between. Tax them at the source as we do with traditional gasoline now. Home garage based refueling stations can easily be regulated just as natural gas lines are now-- by requiring a meter.
I believe the bigger issue which is far harder to overcome is politicians and powerful environmental extremist groups who do not want America to be energy independent because they are financed by OPEC interests.
What's to stop you from taping off your home line after the meter? How will home use be separated from vehicle use, or will they tax ALL NG, home and vehicle?
What do you propose to do about the folks with free natural gas that buy a surplus compressor such as a dive shop unit and convert their own vehicles. A farmer up the road did just that.