I took some pictures of the inside of a CRS328 and a CRS112.

It seems that it's perfectly possible to modify the CRS328 to a solution with backup power on 24 and 48V

There is a 24V psu for the board,
There is a 2nd 24V / 48V psu for the POE part.

https://drive.google.com/drive/folders/ ... sp=sharing

thank you for sharing