I don't understand. You have hand numbness problems but you want to eliminate the easiest remedy---drop bars. I suspect you have a fit issue. What's your bar height? If it's not at saddle height, that's where you should start, IMHO. I have 46cm Nitto Model 177(Noodle) handlebars on all my bikes. My position is as upright as flat bars(if not more so) but I have multiple hand positions available.

I'm relating this to you as someone who also gets numb hands(or did) really early into a ride. Switching position is key. I move from flats to ramp to hoods to drops all the time during a ride. My commute is 40 miles round trip.