Could you possibly put a submersible pump in the pond, and pump water 24/7 into the fathead tank, and allow it to overflow back into the pond. This would keep the water quality up, the tank temps low, and continually bring in zooplankton.
The tank is at the far corner of the property which is too far away for electric. I set it up simply because I had the tank available and wanted to do something fish related with it. Basically a low tech experiment to see what could be done with minimal investment. I never even intended to use the minnows for bait but rather a forage restocking supply.
Next year I will probably take it a step further and do something like you suggest by placing it by the front pond where electric is available. The first year I got the tank I put a single GSF in it and fed it grasshoppers for about 2 months in the late summer after the kids had stopped swimming in it.
