Possible skin you could use for it is the Horse skin I sent you the other day
Transporter/Caravan class
These things I think would be a good balance for it. Transporter is the ultimate supporter and has bad chances surviving alone due to his weapons. Kind of a symbiotic relationship with his teammates. Additionally, his unique ability to carry humans and use a longer hook would help reach places other humans couldn't.
Hammer deploys a safe zone that is slightly bigger than the Scientist's mines. It deals no damage to zombies and lasts 1 minute and can only be placed again after it disappears by itself.
A laser that places a one-way portal entrance on the first shot and a one-way portal exit on the second. A third shot resets it. Defeats the purpose of Taxi
The taxi function can be implemented with an emote or the grenade weapon, whichever is easier for you. But it should be exclusive to Transporter/Caravan
As a potential buff you could also give him a longer hook. This would be useful for maps like Newdust and Canyon.