If I were building a kitchen with a grow cab in mind I would use the floor units rather than the wall. That way you have a double unit with passive intake vents coming from the space behind the cupboard and the grow in there with the lighting at drawer level, next door in the other half of the double unit I would have fan and filter sucking through ducting linked to the other side, you could then build all sorts of insulation around the fan to muffle sound. You could link the extraction system to air bricks in the wall or a dryer duct and remove all that heat.
It could all look like shit that would normally be associated with a kitchen, inside and outside the house.
I like the idea of a stealth kitchen grow, nobody is suspicious of a humming sound with the various kitchen appliances running in the background.