I opened for that reason an 8S BMS. I found a tvs diode with 75V breaking voltage. The Diodeis from "littlefuse.com". So from protection point of view it should be possible ( in my case!!). To be shure, you need to oben your BMS
But netherless i decided to use an 16S BMS for the 48V system. My main concern are the losses, that you have on each protection transistor. So compared with an 16S BMS, you get 4 time the losses with your 4x4S System.