Hey bergie, it would be a challenge to do this and not be a real treasure hunting success at least on a sometime basis if you were to succeed at making a living. I've heard of one guy from Racine, Wis. who was on some tv show claiming he detected almost 80k a year. I can't call him a liar but I've metal detected full time in the past and it's difficult to consider it a living wage. You can only do this if you have several factors met, a large urban/suburbnan location helps, develop a park/playground routine, once a week make sure you hit every site to keep current coinage coming in. Work every target of opportunity especially construction sites, sidewalk and roadwork sites as available. Carry enough gear so that when you hit sites with ancillary gains such as old books, bottles, whatever you can carry them out.
I've gained a lot of knick-knacks, thousands of bottles, hundreds of very old books and other things but cost is an issue. Today gas is the big road trip killer, especially if you're driving something big enough to carry all your needs and finds. I hunt carnivals, festivals, playgrounds and old sites whenever I can justify the travel time and cost. For local events this should be no problem, how far will you go for clad and is there enough to justify it? If I ever did sell everything I've found at fair market value, I'd have to go hunting again to stay in batteries and gas. Despite having little room left to stack anymore, haven't hit the big tickets yet, the gold cache, the most rare bottles, sought after old books or other high end oldies.
MD'ing can become routine, but I still enjoy it immensely and like the little things I find even more reward in those I can return to the person who lost it. Not to start that fight again, just one of my few good points!