Those do have designated pins ... ground, neutral, and hot in the 125V version, and ground, hot, hot in the 250V version. The 125/250V version on another page does designate the shell as ground.
Have you looked at the 'Meltrics' line of receptacles and caps? Pin & sleeve design, thermoplastic bodies, and some are rated as disconnects and satisfy LOTO requirements.
www.meltric.com is the website.
They sent me a sample setup a while back for 'show & tell' at a CEU meeting. I have no idea of $$$ (edit)
I have seen those before. I recall seeing their high ampacity version somewhere in person. I would bet they are pricey.
