Nikon Rumors has published a step-by-step guide on making a Nikon 1-to-ISO hotshoe adapter, so you can synchronise standard flashguns and radio triggers from the Nikon 1 V-series proprietary hotshoe.
The project involves modifying a Nikon AS-N1000 (or generic equivalent) from a coldshoe adapter into one with electrical contacts. Manual mode only (i.e. single pin) is supported, but that’s enough to get basic triggering on the go.
Bafflingly, Nikon offers only one flashgun for the Nikon 1 V1, V2 and V3 mirrorless cameras, the SB-N7. Neither Nikon nor any third-party manufacturers offer an adapter to open up the cameras to work with ISO-standard products, so you can’t take advantage of even Nikon’s own SB-series flashes. Perhaps the Nikon 1 V4 will come with a standard hotshoe, but until then this project, or optical triggering, are your only way to escape the proprietary accessory gaol.
To read the full guide, visit the blog post at Nikon Rumors.