Hi Steve,
From doing this for 4 years and talking to lots of others in the course of things, I'd have to say that the most popular ways of making money in this lifestyle seem to be (in no particular order): workamping, festival/fair/craft show vendor, handyman, construction worker, writer, and internet based businesses. Which is by no means an exhaustive list of the ways in which you can make money on the road, these are just the ones that seem to be most popular. 
As for getting back into the job market, Liam did have a little bit of difficulty finding a job in his field (computers) when we decided to stay here in Oceanside for a while, having been out of the industry for several years, but keep in mind that he had a number of other factors working against him in this: he has no degree (and most computer jobs "require" one), he is 43 with a history of switching employers every couple of years (at least), we are in Southern California (which is positively swarming with techie-type people), and we are in a slow economy. And yet, with all of that working against him, he found a good job in his field within 5 months of starting his search. Yes, that can seem like a long time when money is tight, but we survived on my relatively low-paying clerical job in one of the most expensive states in the country while he was looking.
I guess what I'm saying is, if you want to do this, DO IT! Yes, it can be scary, but don't let that stop you from having fun. Even when we are flat broke, we still prefer this lifestyle to the stickhouse-corporate-9-to-5 thing by far. And we are getting ready to head out and be broke all over again.
Kylie