I'm having a hard time finding a particular hinge I want to use on a
project.

This hinge is similar to an offset hinge, but not close enough for me
to use.
Here's a ASCII sketch of what I'm talking about:
Bd 1 Bd 2 Bd 3
||.......|........||......|
||_______|_______.||______|

..^.......^.......^........^
..1.......2.......3........4

1: Shows the hinge on the outside of Board 1
2: Shows where Boards 1 and 2 abut
3: Shows where the pivot point is
4: Shows the board that I want to pivot

Basically, I want a hinge that will screw into Board 1, go over the
end, pass over Board two entirely, and screw into Board 3. The plan is
to have Board 3 pivot up so Board 2 can slide under it, and support
Board 3 when it's at full extension.
So the hinge itself would look like this:
|............|
|___________.|

Has anyone seen a hinge like this? I've done a bit of searching through
Google, but mylack of knowledge in hinge terminology puts me at a
disadvantage.

Thanks!

-Nathan

PS: My crummy ASCII "art" will probably look funny outside of the
Courier New font. I'm using Google Grounps, so I'm not sure how it will
look on your viewer. Hopefully you'll be able to understand WTF I'm
talking about!