i've never ridden or had interest in flatbar road bikes, i don't understand them, but it seems to me, if properly setup, they will have a similar bar drop as a properly set up road bike. so i'm not sure how that would be more comfortable. i don't think my hardtail or my fully are more comfy than my roadie machine. that said, if you set up dropbars so that the drops are at the same level flatbars would be, then the hoods and flats would be higher....

anyway... i do own a 'city bike' delivered with dirt drops which i bought specifically for commuting. it happens to have clearance for 40mm tires, which i have mounted, and i have ridden it on gravel and single track. i've never had more fun on a bike than when i took that thing offroad. something about a rigid bike with drops that just seems so wrong makes it so much fun.

the only problem is that it is a city bike, so aluminum frame and fork. it would be better for dirt in steel. that doesn't stop me from riding it off road, but it has triggered research into frames. not sure why you're fixed on trek, but there are a thousand options other than those two bikes. i would rec a steel (or CF) dropbar gravel bike to meet all of the needs you've listed in the job description.