Does your "local guy" have a vested interest in promoting the driver CPC as he is involved in providing the training in some way or could he perhaps be covering his ar5e? After all it is not HIS money that will pay for the training is it?
It might be a grey area for some folks but think of your situation. Is it the case that you drive the truck to the site with the "gear" and possibly a passenger or two, the truck is unloaded (whether you help or not) and then sit in your cab for most of the day? If so, then your main activity would be driver and in that case driver CPC would be required. If on the other hand you help with erecting and your employment with the company IS as a scaffolder and not a driver, then I don't think you will need it.
However, doing it is not going to do your CV any harm should you wish to join an industry where you are expected to sleep in your vehicle, see less of your family and be subject to everyone else's working patterns and for less money.