As you catch the bass quickly measure their total length. It might not be easy to weigh them fishing from a raft but get a length measurement. You can evaluate the weight as a general idea of body weight. Always take along a note pad to write down the info. Data over time will help you best manage the fishery to improve it.
I suggest that you make yourself a simple measuring board to help you quickly measure the fish length. I made my measure board from 1/2" wood as a shallow box (similar to a shoe box lid) with the ruler embedded into the bottom. Ideally you want the board to hold some water to reduce slime removal from the fish. Some have used 1/2 of a PVC pipe cut lengthwise and added end caps (see links). Length measure device could be just sharpie marks on the bottom of the device, but some sort of official rule would be best. Others may have good ideas for a simple fish measuring board.
Examples
https://www.youtube.com/watch?v=5W7TaS72Nmchttps://www.youtube.com/watch?v=RwH22tWXG1Uhttp://www.ag.auburn.edu/fish/mediagallery/2013/08/13/fish-measuring-board/https://icastinayak.com/2014/02/how-to-make-a-fish-measuring-board/https://www.youtube.com/watch?v=8Nnm38UcnQ8 
