Yikes, sounds like a scary and confusing proposition. Customers may be confused as to why someone else is visiting them. Once there you would need to know every facet of each individual contractor including what they offer, their business ethic, practices, preferences, pricing, etc.
I wish there was a feasible way for something like this to really work, but for us smaller guys going out and meeting the customers and selling our services is something we just need do.
Most of us know that this is part of what we signed on for.