I think it would depend on the type of work you do. My dad is self employed and he travels often. Right now he's in Sacramento and he lives in south Texas. If your job is the sort where you can have some kind of work order drawn up to "call you out of town" then I'd do that. I'd make the "orders" as an open ended agreement meaning that you are being "called to work out of town" for an unspecified amount of time. If this doesn't make sense then you can PM me and hopefully I can explain it better. If getting "called out of town" Doesn't work for ya then I'm at a loss.
"It has been said that politics is the second oldest profession. I have learned that it bears a striking resemblance to the first."- Ronald Reagan