I haven’t found a way to power cycle the RTL-SDR remotely, you could try to find a remotely managed Pi power supply I know @ea5wa seems to have one.
Lowering the sample rate will reduce the decimation value and therefor lowers the reception quality.
At the end I replaced all my SDR devices with other models and haven’t experienced any problems after that.
Have a look at the meta data of all my stations to see what SDR is used.
Jan | PE0SAT