I ordered some VGA PMod adapters from Digilent last week, and I'm happy to say that they fit perfectly. The mechanical connection is very solid, far better than any card edge connector I've used. Near as I can tell, the electrical connection also seems to be good as well.
I haven't had the chance to reprogram the FPGA design to use this particular adapter yet. I will update with my results upon completing that.
The only thing which sticks out to me, besides the height of the connector, is ... the height of the connector. And, its orientation. But, if you can strain-relief the monitor's cable appropriately, it should not pose a problem for the BX-Plorer.
(Aside: my experience with how well this PMod fits into the sockets on the BX-Plorer has convinced me that the right way forward for the Kestrel-3's backplane should be 2x40-pin RC80-compatible connectors.)