Interesting stuff, Ken.
It looks like Josh is using St. Brendan's Isle mailing service, located in Green Cove Springs, Florida (a small town just outside Jacksonville), as his PO Box. In addition to being a mailing service, St. Brennan's Isle also helps clients gain Florida residency, which pretty much confirms that Josh is currently in Florida, likely somewhere around the Jacksonville area.
Mail Forwarding Services for Cruisers, RVer's and people who travel. That is our Specialty! We have been providing mail forwarding services since 1988.
www.sbimailservice.com
en.m.wikipedia.org
Now, you said before that Josh said he lives in the middle of a swamp. Green Cove Springs just happens to be near the Santa Fe Swamp, which is located in Bradford and Alachua counties. Josh most likely lives in Bradford county, since Alachua is much bigger since it is home to Gainesville and the University of Florida. Starke, the largest city in Bradford county (despite only having a population of 5k), is a possible location for Josh, since it is right next to the Sante Fe swamp and there is a highway that directly connects Starke to Green Cove Springs.
en.m.wikipedia.org
en.m.wikipedia.org