Sounds like you have it covered assuming you aren't going to evap the water in the sump. Fish and corals will be fine foodwise.
In the future look at getting something to help with auto top off just for the sake of having one less thing to do so frequently.
There is tons of info on them on the web. I just use a gravity fed
float valve by Kent. But, there are lots of electronic
float switch schemes out there (although I've always been afraid they'll stick- ask CyberChef).
But, don't go installing one of these before your trip- you'll want some time to observe.