Here's the geo of my old Alliance All-Road. This predates the "gravel" scene and can really only handle 35-38mm w/o fenders. My road bikes have a bit less trail than this ( 56-57mm) using a slightly steeeper head angle/rake, but have the same bb-drop
Note: the trail listed in the geo is for a 25mm tire. Fatter tire=more trail.
This geo was pretty darn comfortable on long rides and handles quite well in hilly road races.
Trail and low BB are pretty important considerations for the given intent IMHO.