I'm not sure if that Sunrace "cogset" is a cassette or a Free Wheel. I know Sunrace makes 8 speed freewheels, so????

IF you bought a 2nd wheel (I'm currently buying a 2nd wheel set for similar purposes), I'd just have it equipped with it's own cassette.

The reason--??
You will probably be riding under different conditions when you are using the different tires. With the knobbies, a "mountain" cassette would probably be more appropriate, while with slicks, a "more" road friendly cassette would probably make sense. (The slicks roll easier on pavement, so you can utilize a bit higher gear)

Having the cassette already mounted will greatly speed up the swap.
Just have your chain long enough to handle the largest cog used on any wheel set.

BTW, I'm getting a cheap 700c wheelset & 9 speed cassette for $108.50 delivered from Niagara Cycles through Amazon.