I like your thinking...I tried it myself.
I used a few different approaches. But what I found is this:
Using a 12v->12v dc-dc buck converter to keep miners going with a battery directly to the battery after the buck converter.
The buck converter was 50A max continuous. Before this setup I tried the chips plugged into the battery directly which fried some chips after a few voltage fluctuations.
This is why you NEED AN INVERTER to stabilize your output voltage.
When the buck converter was connected into the battery it also fluctuated with clouds and such it shut the miner off when it got too cloudy and then would turn it back on but the miner would have to reset each time and it was not efficient at all. In theory I wanted to skip the battery to save resistance and get rid of having to replace them or use them. However I have found that batteries offer a "cushion" for the voltage fluctuations to be less and yes it sucks converting dc to ac then ac to dc again but if you don't do this it's not stable voltage and will fry stuff or at best just stop functioning for bits of time unstable.
In short the losses from conversion are necessary as a trade for stability.