I took two different approaches for a rain coat.
As a low bulk and low weight solution I have a surplus poncho. It is a little too loud for hunting but otherwise satisfying. As an overcoat it allows me to keep my stuff in the pockets of my regular clothing and dress for the temperature. It also helps to keep the hand dry and warm (just do not stick them out).
I also have an oilskin riding coat as standalone solution. It is long and easy to maintain. It is rugged and has a fairly distinct style going well with my Akubra hats.