Hi Thomas,
I would attach myself to the easiest thing you can reasonably manage. From your post, the easiest thing you could tackle to gain a foothold would be farm waste.
Finding ways to use biomass is not hard. Pile it somewhere and it's gone in a few years. If there are forward-thinking farmers in the area, you could propose a biomass utilization scheme to get those people to capitalize on it first. When you're one of the few utilizing an abundant resource, there are serious advantages.
I imagine the most difficult thing in that realm is transportation. It's much easier for them to pile and burn. But if you could work out the logistics and the timing (making sure you have a vehicle sitting there before the fire gets lit), you could make a lot of people happy.
As for the plastics, I've seen images of Guiyu and they are extraordinary. I don't think you would have much luck with convincing people not to melt the gold, copper and other precious metals out of the plastic. For that, your best bet is finding a way to have it done via industry. They created the things, they should be responsible for the re-use.
One suggestion would be to use plastics in building materials. It's not an ideal nor a long-term situation, but it does have the benefit of locking up dangerous chems in structures. It's a little better than burning. There's a documentary about this guy from arizona called the Garbage Warrior. He converts glass and plastic bottles, and old tires into Earthships.
With
enough creativity, you might find that you could re-purpose some of that plastic to useful ends.
Oh, and then there's that guy that made a reverse polymerization thingy. He converts plastics into
gasoline. On a small scale, it might be worth looking at that. Really it's just burning in a different way. But you get the add-on of fuel. I think that it does take electricity, so your
energy conversion rate still isn't very great. Could be another pie-in-the-sky kind of thing.
There's also the MIT study of an amazonian fungus that feeds on plastic. But I think that's a little magical thinking there. Getting that going on a large scale is not within our means as of now.
Good luck,
William