Ehh, how sandy are we talking? If it's sandy enough to sink in, then 32mm will be a pain even with a tread. You'd want a wide contact patch for that; it's more about bike control than grip at that point. If it's closer to 'a little bit of loose sand' than you should be fine. FWIW the GK SK are fairly grippy, just a hair more grippy than XPlor MSOs in my experience. I ride the 40mm version and usually have no problems unless the sand is deep enough for the tire to sink. You'll need to watch out on descents more so then on climb.
Another one to look at would be Vittoria Terreno Dry. I really wanted to get a set of them but they were on backorder for weeks; should be a faster-rolling tire than GravelKing but nearly as grippy. Not sure what the stock looks like this year. And, of course, there's the Schwalbe G-One and the various offerings from WTB though not all are made in 32mm.
Just for reference, this kind of stuff is perfectly doable on 28mm slicks but you do have to be careful especially on steep terrain; 32mm tires with tread would give you much more confidence.
