My suggest is Transporter should be NE role. I think Transporter role will be better and fun to play when it is NE.
Why I think like that?
1. To my opinion "Transporter" role is discordant with town. For example it isn' t roleblocking anyone or using dead peoples roles or giving +2 vote for town or taking informations from deads or etc.
2. Transport role is a handicap for town. Transporters often ruin "Tis results" or let vigilantes to shoot wrong targets.
3. It has got a low chance to let mafia kill other mafia but this chance is too low.
How will it be, If Transporter role is NE
1. You don' t have any treat for ruining Tis results or let vigilantes shoot wrong targets.
2. You can choose your side. You can play with either mafia, town and Neutral Killing.
3. Your only goal is survive as survivor but you will have a huge affect to game.