i see your frequency is low in < 2khz. so simply why not use digital filter using a small controller with sigma-delta ADC / DAC. also because you have high order filters means more component count on the board. and of course you will suffer form component degradation.
If somebody really wants to design a filter, please start with the low pass and design it in LTspice with the LTC1068-200 (8th order filter). Meanwhile, I' quite sure to take this circuit. Then, I could give you further hints. Thank you.