Here's an idea book you may like https://www.houzz.com/magazine/houzz-tour-charming-rustic-lakefront-cabin-in-minnesota-stsetivw-vs~2010542
Trim is just for cosmetic purposes, so, what the trim color should be is hard before the walls are put up

Stained wood is always a more expensive upgrade over painted. It's more time intensive to do and has to use higher quality products. Which is why you see so many protest against cheapening a home by painting over the original high quality woodwork so that it looks like a builder's tract house.

If you want a rustic look to your home, you need to go with wood. That's what rustic is--wood.