Not dog related but...
Are not some passengers more likely to require a moisture absorbent mat?
What about the ole footy teams...
Projectiles are dangerous... Remember that one Sheepie
The point is that there are rules there for a reason, maybe this has highlighted the fact that the rule has never been enforced upon you before.
In the NT it was made illegal to carry an animal unrestrained in the back of a ute - reason animals safety and or proectile animals.
Wouldn't it be in the interest of the Lab to be placed in a shoulder/leg harness (similar to the walking harness) and be restrained to the base of the chair (like the oxy bottle is). After being placed on a moisture absorbent mat? This would cause no discomfort and would abide by the rules...
Woof woof woof...