Ah, that is the western portion of the Great Western Trail. They do not connect directly, but I do know there are expansion plans for this trail.

I live further east, so the Prairie Path, Great Western Trail (Eastern Section), and Fox River Trails all connect to create well over 100 miles of (mostly) well-maintained bike paths. Only the Fox River Trail is paved. If the western portion of the GWT ever does connect to the Fox River Trail, you will have an nearly endless trail system at your disposal.

I haven't ridden that western leg, but I have ridden on everything from 700x28c tires to 700x38c tires on the other crushed limestone paths I mentioned above. I definitely appreciate the wider tires when the trail is wet or early in the season, and would like to try 40c or wider. But I don't think you need one of the more aggressive gravel bikes for this trail system. 35c is fine 90% of the time, which you could even fit on some road endurance bikes, since there aren't many loose stones on the crushed limestone paths to jam in to your fork and frame. Anything that fits you and can fit 35c tires would probably work great.

Another consideration is that crushed limestone puts a lot of dust on your bike, so you might even consider some fenders. You will get in to a routine of washing your bike.