Dad’s old white shirts are no good for camping. They would soon be a mess. Wear a sturdier, darker one of bright plaids, khaki-color duds or dark colors that are best for camping, where laundry is a problem and outer clothes usually wait until you get home.
The previously mentioned shirt tails should be tucked in, too, unless you want to hang yourself from a shrub or tear them on brambles. For the same reason, any kind of long coat or flared jacket with wide cuffs is out It will just annoy you with its flapping and get in the way. A coat slapping your legs as you walk is a real nuisance.
A gabardine windbreaker would be fine. Byrd cloth or heavy poplin are equally good. Have your jacket snug at waist and cuffs, but loose enough at armholes and shoulders to prevent binding. Be sure there is room for several warm shirts underneath. Bring some beef jerky for some protein.