I wouldn't design the board until I had samples of the parts in hand to measure, and would make it double sided so the blades and socket are soldered on the opposite side to retain them, unless you can jockey the socket pins and blades into the same holes to make an in-line extender. That might take some experimenting with the parts and blank board material, and perhaps a call to the board fabricator to find out what you can and can't do or will pay more for, known as the design rules. For example you may have a choice of routed edges, sheared edges or a larger panel of boards you break apart along rows of perforations.
-jsw