might try a small mountain feed bag on the bars, a small bike bento bag, or some other small frame bag, like those little triangle bags, or different outer wear. for example my MTB shorts have lots of well designed pockets, maybe there are equally well designed long pants with strategic cargo pockets for the sport?

these (long shorts?) appear to have a strategic pocket on the left thigh Urban Cycling Apparel The Gravel II 1/2 Pants - Long Mountain Bike MTB Baggy Shorts, Magnet Pockets