anethole does float after steam distillation though. seen it.
well thats a start
seriously though I do like the idea in general as it could well prove its worth in time

As for small bushes containing saffy in the US...idk but I do know that its probably more than you think..google the question and variations thereof "safrole containing plants/in the US" and poke around I think you'd be surprised

Surely you know of the sassafras trees around

and in many places down south I believe you have similar camphora cinnamomun infestations like we have here!

(Yeah you heard me right
"Infestation"
)Introduced to the contiguous United States around 1875, Cinnamomum camphora has become naturalized in portions of the states of Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, Texas, and South Carolina.[2] It has been declared a category I invasive species in Florida
The problem/question really is firstly "do they contain viable amounts and percentages of oils for extraction? Secondly "what percentage of the oil is the desired compound?" these babies do

Go and get yourself a few (hundred

) kilos of rootbark and juicy shoots and come back and steam distill them, more than likely the oil (around 5% w/w) of which maybe 10% is safrole sometimes more sometimes less, it depends on lots of things (position of plant, time of year, part of plant taken etc) fresh has yet to work out any better methods of working out what parts of the plant to take to extract, and so he just relies on the smell of the plant matter and when chopping the bark. It's usually pretty strong on growing plants.
Fresh uses a 'mini' mattock same shape as a big one but about the size of a tomahawk with a handle 40cm long and a 'head' that's about 25cm end to end.
sharpen the flat end on the 'inner' (standing on it's handle like a 'T' that is the bottom/lower edge) quite sharp and you have something that works like an adze and can carve off bark deep chunks with ease

they're fuckin great and make gathering the bark easy

They're BIG trees with big roots and they often grow in clumps
http://en.wikipedia.org/wiki/Camphor_Laureland of course
http://www.erowid.org/archive/rhodium/chemistry/safrolefaq.html 
definitely worth checkin out if you haven't

Fractionating the oil obtained from steam distillation to obtain a pure product is virtually a given.
Maybe with some of the higher safrole content oils, freezing the safrole to separate it from the oil can be done as safrole has a very low mp