If there's plenty of work in it then you're off to a great start and this is a niche and nothing you couldn't do remotely.
I'd start with putting a website together to showcase what you do and you can easily direct people there and get some info about SEO.
Do contact the people and companies you've worked for in the past!
In all honesty, I don't promote myself a fraction of what I should/could but I've gained a new skill set so I've got to do the same and pull my finger out a bit.

Yes, it's a bit of a slog but you can chip away at it and you'll get there.
I think there's a saying about "Build it and they will come" or something.
It may be much more reliable than finding a seasonal gig in a nice place in the sun.
It probably sound a bit daunting to build up your own freelance client base but think of it this way.
If you want to be a semi-nomadic freelancer lifestyle then if you have your own client base then you will have much more flexibility, freedom and control than if you were relying on in-house gigs.
You can go where you like not just where the work is.
Say if you wanted to visit Spain.
Most of the design jobs seem to be in Madrid so the cost of living may be higher and so on and Madrid might not be for you but you're tied to it.
A guy I know has travelled the world, through South America and (I think) is and has been for a while in Buenos Aires where the cost of living is lower and he gets more bang for his buck.
I still get tempted to go nomadic myself and I was watching the Ben Fogle programme "Lives In The Wild" last week where a couple and their two kids fitted out a bus as a motorhome and travel around NZ.
Their cash ran out so they started a blog about their travels and through advertising, they make their income that way.
Like you, lots of people are interested in this lifestyle and want to know more about how to make it happen.
Oh....and the book "4-Hour Work Week" is supposed to be good although I only made it half way through.