Bashomatsuo, the link you gave for WWOOFing does not have any caveats that I can see other than don't expect a free bed for nothing.
Really? I thought I did a good job of warning people, particularly about that place...
The caveat it should have is that it is not legal for a traveller on a tourist visa to WWOOF or the like in many countries.
The statement, "is a way of getting around the fact that one may not have a work visa.", is absolutely INCORRECT.
YMMV. That was exactly how it was "sold" to us.
They argue it is 'volunteering', not 'working' but Immigration in many countries do not agree.
I have heard of issues you describe, indeed WWOOFing appears to me to be full of nothing but legends and stories. On the other hand, It's not hard to get a working VISA for Australia and NZ (if one is British and under 30 - as I was... just). However, when we tried to WWOOF in Japan we had a very negative experience with the WWOOFing organisation, which I will be covering on the site in April.
As you asked so nicely - not really - I have put a warning on the bottom of the article using your text.
For the OP, I met a guy (in Agra) who cycled from Aberdeen to Adelaide and then Adelaide to Aberdeen (the other way). He did all this while recovering from ME. I also met a man who walked across Europe, dressed as Charlie Chaplin, and demanded (and got) an audience with the Pope. Sure, your plans need to turn from fantasy into reality - but that's a good thing.
Regards,
Basho