Ok aside sh*ting on Bitmain which I understand. I played around with some compressed PVC panels and results are pretty good. Fan on front is Delta TFC1212 5500 rpm.
And with this setup it does not matter if internet connection is lost or pool is not working there is no chance to burn anything...
Easier to just remove the PWM line on the stock fan (I prefer to pull the connector out of the plug then electrical tape it, some folks might prefer to just cut it as that's easier), then it runs at 100% all the time for best cooling.
Not all the time some fans will stop spinning if you remove that PWM wire. and others will spin 100% RPM it depends on the fans controller chip built into the fan. so like I said it depends on what fan.
I had both fans wired directly to the PSU "both S5 original fans" then I remove the internet connection and I was still able to view my miner status page. The temp shot up well above 80c "90 to be exact" with both fans still running at 100% RPM. I manually shut down the PSU because if I let it continue it would have burnt up. so your idea will not work on some of them I know mine it did not. But nice idea though.
Did you simulate the problem when you modified it to see if it really works and does not burn up ?