The current sensing method of the circuit you show turns on Q2 when the voltage drop across Rsense reaches about ~0.65V. At 48A, Rsense is dissipating a whopping 0.65*48 = 31W. Since the drop is ~0.6V, it will screw up the regulation of the 5V supply unless your supply can remotely sense the load voltage, and you can connect the remote sensing downstream of the current limiter.
The Vbe at which Q2 turns on is strong function of temperature, so this is a pretty crummy current limiter. Besides, regardless of what you use for Q1, if a current overload is detected by Q2, Q1 limits the current by turning partially off, meaning that the dissipation in Q1 could go very high... Imagine that you short the supply. The current is limited to ~50A, and now the entire 5V from the supply appears across Q1, meaning that it is dissipating 250W!!!
A much better solution is to buy a supply that includes current limiting built in. For example, I recently bought some used MeanWell 650W 15V switchers that have pot settable output voltage and pot settable current limits on Ebay for $30.