By using the Hepco Becker mounts & 45 liter bags, it puts the O/A width at just a tad under 40". You can subtract 2" for the 40 liter bags & 4" for the 35 liter bags. I'm looking into alternative mounts that would be narrower. The Bumot mounts should put the O/A width in the 36-37" range. But I don't have a time line on those yet. Not really familiar with Holan, but the quality of the Bumot is definitely high end. I've been riding on Sargent seats since '98. Have done several 1000 mile days. I've tried a bunch of different seats, but for me, the Sargent works best.