I think your plan makes sense.

FWIW, I used to only own a hard-tail mountain bike. And I rode it more on pavement than on dirt. At first I kept the knobby tires on it, and eventually I switched to slicks. I used to do 50-mile rides on that bike, on paved trails.

Since I got a road bike, I put the knobby tires back on the mountain bike. But I have used it since then for paved riding, for some family rides on the National Mall that involved a large group of children and very slow riding with sudden stops. I figured the wide tires would make it easier to remain upright under those riding conditions.