I guess it depends on what your definition of "bush" is. I learned a while ago not to get into a pissing contest with an AK pilot, but there is challenging flying outside of the great white north, and even outside of the mountains. When i came to work for my current company, i didnt even know this type of flying existed.
If by bush you mean ak flying, then i cant really help you with that, but if you're looking for a challenge and something different, then i can give you a different perspective. EX: This morning i landed in about a 2000 ft pipeline canal, over power lines, with a 25 kt tailwind, came up short of my tie up (a mistake) ran aground, had to pry myself out of the mud, spent 20 minutes trying to turn the plane around, hit the bank three times, finally got the plane turned around, put scratches on the wing tips, finally made my tie up, then the cleat broke off because of the wind, almost fell in, smoked a cig, loaded up, and did it all over again.
It might not be mountains, and im not trying to get into it about whos flying is the hardest, im just trying to open people up to different types of flying, because i didnt know it was ever possible to make a living like this until i was lucky enough to get a chance to do it.
Good luck