Hi!
I’m not sure, but it might be possible.
1. On the General Options -> Behavior panel, set:
Minimal character count to trigger search option to 0
Trigger search when changing a facet on settings? option ON
like so: http://i.imgur.com/CbWRsTu.png
2. Make sure the settings are visible by default: http://i.imgur.com/hPN75O5.png
3. and then, to hide the search bar, use this custom CSS:
[html].asp_main_container { height: 0px !important; }[/html]
That seems to be working on my test environment.