I've been debating this for a year or two and decided I'm going to do this with my kids to see if we can put a tree somewhere, watch it grow and see what happens. Would be great if it made it a year or two and actually produced figs.

I'm in RI so will need a good cold hardy variety to do this with. Besides Hardy Chicago, does anyone have any other recommendations?

All of my trees I overwinter inside for the winter so don't have any first hand experience with dealing with the elements.

Who else has tried and succeeded with guerilla plantings?

Just a thought. If I were you, I would gamble and try to go with the most common varieties available such as Brown Turkey, White Ischia or Black Mission or improved Celeste.
You probably could get a large one ready for the yard if you don't wish to wait. I might even try the improved Brown Turkey if available.(I prefer the improved Celeste over Celeste).
I've seen a lot of fig trees in around NY city which is zone 6a and 6b. I recently saw someone in Broooklyn with a tree in his yard next to a wall. It was just as big as the large ones in your shed. The way things are over there is that they usually are protected from the wind as homes are built one next to the other, which might create a microclimate for the trees to thrive. I believe that if you plant your tree close to a wall you would do well. What will hurt it the most is the wind.

Do a search for cold hardy figs. There are several that deserve a look.

Interesting idea.  I've thought about this.  I've got a couple spare Almas and Excels, and I'm thinking one should end up in the corner of some park...

Mike --

I'm in Bristol, RI.  I've got 6 plants in ground (more coming), which have survived 1-3 winters outside (with protection) with no losses.  If you want just one plant, I'd say Ronde de Bordeaux.  But there are lots of possibilities.  Send me a private message and I'll give you the name of a very good local supplier of both plants and expertise.

Joe