cutthroat sizing and alternatives

Hi all. I need some advice about sizing. I have a stock "V1" version of the Cutty (2019 before new release). I've been fitted at my LBS and have been told by them and others that the bike (medium) is the right size for me. The reach is indeed right but I really have no margin in stand-over height. I'm 5'8.5" with 31" inseam. I can live with that but I have a "on top" rather than "in cockpit" feel while riding... This translate to less confidence when dealing with rough terrain or going downhill. I recently did the Arkansas High Country route and had the impression at times that the bike wasn't a good match for it/me. I'm new to bikepacking so perhaps the Cutty demands more experience and stamina that what I have... I'm starting to wonder if I need to downsize or perhaps look at switching bikes. Advice? Suggestions?

Bil