pyrohaz - the only previous mention of this topic I can find was http://forums.leaflabs.com/topic.php?id=533#post-2775
I don't know what the outcome was.
Have you got access to an ordinary Arduino protoype shield? IIRC, the expansion header on rev5 was moved onto a 0.1" grid, and so should be on the same grid as 3 of the other 4 headers, and hence may 'just work'. But I must add a 'health warning' because I haven't checked.
Another alternative, if you can use Eagle, and can either make PCBs or are willing to buy them (try dorkbotpdx.org's http://oshpark.com/ or seeedstudio.com's PCB service), is to design your own.
1. Get the Eagle CAD for rev5 e.g. from github,
2, throw away EVERYTHING on the schematic that you don't need, leaving only the headers.
3. switch to the PCB layout, and the headers and board outline should be okay.
4. tear up *all* tracks,
5. set the board layers to "(1*16)".
6. make yourself a nice pattern of holes (say 1mm diameter) on 0.1" pitch, copy it across the board, and create a "stripboard" pattern which suits your purpose.
7. get your design made.
(Full disclosure: I am not a member of LeafLabs staff.)