Pete,
With the utmost respect, you have come up with the fairly typical response to this type of question. I don't need one because xyz.
Of course a Truck Mount is a marketing tool, especially for the developing business. In my experience people are looking for something more than a guy turning up with a mickey mouse machine to clean their carpet. That doesn't mean that all portable machines are Mickey Mouse, nor is it casting aspersions as to the professional qualities or otherwise of its operator, but the fact is people don't trust people with portables anywhere near as much as they do the guy that's willing to invest in state-of-the-art equipment because they see him as a committed professional person. That's not what I say, it's what countless of my customers have said for decades, the very same customers upon which I have built my business.
From a marketing perspective you can go out there and do demos on pub, restaurant, night club carpets, THE DAY AFTER THE PORTY GUY DID IT and make sure that he never gets the business again because of all the crud he left behind.
Truck Mounts give you the edge. Truck Mounts give you the ability to clean anything, big, small, dirty, filthy. In the right hands Truck Mounts practically print money.
Simon