First of all, I want to say how much I love FT advice over TripAdvisor's.
On TA, you would have had a dozen posts how to properly see the Falls, you need at least a week. Seems everything requires at least week.
On FT, everything can be done over a layover. Love it.
I agree with benbeng. It's a doable plan. It will require moving quickly, but will work.
What I would suggest is hiring a guide. When our time at a destination is short, we always do it. It helps maximize time and avoid wasting it figuring stuff out.
On our recent trip to LVI we used Chris
http://www.christourszambian.com/
Very nice guy and reliable. For a couple of hundred bucks, you will have a taxi driver and a guide to help you avoid wasting precious hours.
He could pick you up at LVI, drive to the hotel to drop off bags, and on to VicFalls. He'll leave the car on the Zambian side, walk with your over to the Zim side, guide you through the park, return back, show you the Zam side, and drive you back to the hotel. Very doable in 6-7 hrs you have, and well worth it.
Probably just a hundred bucks or so vs having separate transfers from airport to hotel, from hotel to Vic Falls, from Vic Falls back to hotel. But massive improvement in logistics and reliability.