Something to consider in your research. Some portrait photographers did "Home Portraiture". Meaning they traveled to your home and did portraiture on the spot. One photographer I know of that was notable in this arena was H.T. Koshiba from Providence R.I. & New York, New York. So, if they were a traveling photographer, I would assume that their gear must have been portable or small enough to be portable. Climbing stairs, setting up in small homes and apartments, etc . . . it must have been great fun.