I googled for quite a while, but there does not seem to be any in the US or Canada. It seems like there may be some in Europe, in the Czech Republic that I found listed here:
https://darknessretreats.wordpress.c...ss-facilities/
However there doesn't seem to be enough information anywhere to actually schedule or book anything (it doesn't help that the retreat websites will probably be written in Czech), however if you scroll through them all there are some links where you may be able to contact whoever owns and rents out the cabins. This is one of them:
https://translate.google.com/translate?depth=1&hl=en&ie=UTF8&prev=_t&rurl=trans late.google.com.au&sl=auto&tl=en&u=http://www.terapie-tmou-u-brna.cz/