I'd get a Big Newspaper boy Wald front basket, and carry your back pack,
or the messenger bag in it..
maybe a couple square buckets on the rear rack.. panniers
with snap lids .. that covers dry, and cheap..

Hot sticky-humid Missouri .. I memory serves me well,
Id have a hard time coping with a back pack on walking .
and I haven't been back there in over 40 years ..
The River is still there .. so time wouldn't change things...