www.volunteer.gov/gov
This link to US Forest Service, BLM, National Park Service et al will get you opportunities at the
Federal and State level. Wife and I hope to go full time in a year or so and plan to do two 4 month
stints and travel north or south during the two month between, while we enjoy living off grid.
Lots of opportunities to swap some labor for a full hook up parking space in some great venues.
Big name parks (Grand Canyon, Yellowstone, Yosemite) are typically gone early by those who return
year to year. Occasionally I see an ad for one of the big parks, but they don't last long. If you visit
one of the parks, stop by the store and ask to speak to the Head Honcho, let them know your interested,
and see if you can fudge yourself to the front of the line. . . .
Good luck ! !!