If the billboards were to quote WTS publications how could wts sue? It isn't slander nor is it defamation, so what could they go after you for? If the board quoted Russell something like
Headline: God's Guided Organization without a doubt
"1914 is the end not the beginning but the end" Wt xx,xxxx
"1874 definite proof of Christ's return" - wt xx,xxxx
"1925 has more bible proof than 1914" -wt xx,xxxx
Organ transplants = canibalism - wt xx,xxxx
bottom: But that's old light now, God's spirit was just testing
BTW quotes above aren't exact but the point is how many witnesses have any idea about these teachings. Nothing slanderous just quotes something to make people think :) Price would be an issue but if one could talk to a lawyer before doing something like this to double check on legality and what could happen, hey it would be funny, I wouldn't mind throwing in some cash for a fun cause :) Isn't there any x-jw lawyers that could advise us here?