Is it possible to use i2c accelerator to multiplexer input?
Definitely use a shielded cable to minimize environmental noise. Also instead of going with higher speed of I2C, lower ones might be less prone to noise.
I know i should extract the use full things from the link I am about to give, but its just to much: https://hackaday.com/2017/02/08/taking-the-leap-off-board-an-introduction-to-i2c-over-long-wires/ In generall it says to use lower ohm resistors, just not to low to not draw too much current. This goes without using a accelerator.