I usually get ~ 700 miles out of my trail runners, about 3 pairs/year- that's on varied single track trails with usually some 20-30 mile trips to bag various peaks. The tread still looks fairly decent, but the midsole components eventually start to breakdown. When you really notice it is when you switch to a new pair and you're like ahhhhh
Trail runners aren't the answer for every trip, but they are the answer for a lot of trips.
A recent 32 mile day through heavy rain, light wet snow, rock, mud, snow, a [bleep] ton of fords and wrestling with a lot of blowdown. This would not be the trip you'd want heavy leather boots, they'd be soaked within minutes, would then weigh even more and not be dry for days.
If you haven't tried them, pretty tough to speculate how they are going to work for you. You just might be in for a surprise
Are you making any footwear or sock changes for these crossings or just wear the same shoes and socks for everything for the day?