One thing for the OP is that there are still at least some wetplate practioners in the third world, primarly ( i think) the middle east. These are often street photographers peddeling little tintypes. I met a photographer from Egypt who told me this is still fairly common as the chemistry is still cheap and avaliable.
I just did a shoot using an old bank vault (read no ventilation) as a makeshift darkroom. I wont work without ventilation again.