In addition to the fact that one Space = 0.5 dTons is (at least from my PoV) way too large (0.25 dTons/Space would make more sense), there's the additional issue that in High Guard you have acceleration benches, which seem pretty much like what most vehicle seats are, and acceleration benches accommodate 6 passengers/dTon, which is 3X more than can fit in vehicle seats.
I think a good compromise would be to change vehicle Spaces to 0.25dTons (with seats still taking up one space) and also to only allow acceleration benches to accommodate 4 passengers/dTon. Since presumably you want to keep air rafts at 4 dTons, given them a 1.5 dTon cargo capacity and allow them to hold 7 passengers. You might also make crew stations in vehicles take up 2 spaces (ie the same 0.5 dTons they do now.
So an air raft would have
16 Spaces (4dTons size)
Cargo = 6 Spaces (1.5 dTon)
Drive seat = 2 Spaces
7 Passenger seats = 7 Spaces
Satellite uplink comm = 1 Space
I'm including the satellite uplink communicators on the basic air raft, since it's often used as a ship's vehicle, and that addition only makes sense to me.
3 Spaces/dTon might also work, but seems clumsier.
I think a good compromise would be to change vehicle Spaces to 0.25dTons (with seats still taking up one space) and also to only allow acceleration benches to accommodate 4 passengers/dTon. Since presumably you want to keep air rafts at 4 dTons, given them a 1.5 dTon cargo capacity and allow them to hold 7 passengers. You might also make crew stations in vehicles take up 2 spaces (ie the same 0.5 dTons they do now.
So an air raft would have
16 Spaces (4dTons size)
Cargo = 6 Spaces (1.5 dTon)
Drive seat = 2 Spaces
7 Passenger seats = 7 Spaces
Satellite uplink comm = 1 Space
I'm including the satellite uplink communicators on the basic air raft, since it's often used as a ship's vehicle, and that addition only makes sense to me.
3 Spaces/dTon might also work, but seems clumsier.