Personally, I feel as if when you are getting paid for a job, you should be considered professional. Anyone who gets a paying gig does have the responsibility for being portrayed as a professional. The way you act, react, speak and respect your clients will determine if you are a pro or not. People that do not act in a professional way will not last in this business.
Yes, I have a day job also but, in the 5 years that I have been doing this, I have built my business on being professional and provide the client a good product. Repeat business is what has taken me from a bar only business to one who is bidding for festivals and larger indoor venues with regional acts.
Don't try and BS your way through it. If you don't know something or you find a job thats over your head, admit it and be a true pro about it. If you have to cross rent to get it done, so be it. Just make sure you are smart about it. I have been given the task of not only being the audio contractor in many cases but, also I cross rent the stage, roof, generator and lighting if it requires more than what I can provide. Yeah its hard work but, to me its very satisfying to see it all come together!! As a result, I have a huge sence of self satisfaction for a job well done.
Currently I have had to obtain a CPA to help me with my business side of the equation and in turn, it has allowed me to grow in a different way. Being organized at a gig shows your professionalisum. Being organized in your business structure and on the accounting side is not only smart but also a trait of a true professional.
Bottom line, if you act as a professional, provide a professional product no matter what type of gear you have and you are percieved as a professional in your clients eyes, IMO your a Pro!!