To my knowledge, 48 simultaneous PWMs at 100hz with 8-bit resolution is not possible using a single PIC.

However, that many channels using BAM (bit angle modulation) instead of PWM is very possible. Might even have time left for the DMX reception.

Bit Angle Modulation (BAM) in a PIC
http://www.picbasic.co.uk/forum/showthread.php?t=7393
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