yes.
That simple solution works. But you may be able to dispense with the float valve as well.
check out nanoreef and see what some folks with pico tanks are doing with pet bottles (meaning hamster water bottles) for simple ATO with no moving or mechanical parts, like this one on a 1.5 gallon tank...
5554b48857ad9681.jpg
I don't know how well this would scale to a larger tank, or larger resevoir, but it's worth a test, with and without a float valve.
Try it out. Let everyone know. Be a hero.