When I was single and flying a lot, I'd be gone 4 days at a time. I had two cats.
They had an automatic self-scooping litter box, automatic feeders and water bubblers with a large reservoir.
When I left, I'd leave the stereo in the family room on low for them with the channel set to something with voices-- usually NPR.
The cats did fine. 3-4 days was (and continues to be, if my wife and I go out of town for a few days) a non-event and they were always happy to see me-- they'd both be by the entryway when they heard the garage door opening.
Of course, NPR might not have been the best choice as sometimes when I'd come home, they'd be marching around the room with little kitty signs over whatever the hot topic of the week was!
R.