Hi,
First of all, your choice of divider resistors to derive Vref of 2.5V from 48V output is not adequate. Even if you adjusted the trimmer to the bottom, you'd have 2.697V whereas you need 2.5V. I'd advise to not use a pot. Make simple voltage divider calculations to derive 2.5V from 48V and use fixed resistors.
For Rsense, we can't say much for the info you have given us. You haven't told us anything that portrays your peak inductor current value. Moreover, a fixed resistor (not wire wound) will be better suited for current sensing.
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Also, I do not have time to make calculations for your converter but your input and output specs has caught my attention. Can you explain those?
What about UVLO?