Hot gas bypass in two-stage cascade, low temperature system?

I am trying to build a system that will allow me to cool a small heat load (say 100 watts) down to -55°C, but I also want to be able to have the same evaporator run at 100°C and at any temperature between those two extremes with that same 100 watt load. I've made similar systems in the past that will do -30° to +120°C with a single stage sytem by adding hot gas bypass to the compressor so that it can run with anything from full load on it to no load on it. I then added a pulse width modulated valve to regulate the amount of refrigerant that goes to the evaporator so when I want to go to higher temperatures I just reduce the amount of refrigerant sent to the evaporator. I don't see any reason I couldn't do this same thing on just the low temperature stage of a cascade system, but wanted to see what others thought before I build something to try this. Thanks for any input.