Can environmental elements (weather), and outdoor activities affect a hair transplant at 8 months post-op?

After eight months post op, your transplanted hairs have either taken or not taken.  This actually happened in the first few days after your surgery.  So at this point weather would not affect your transplanted hair's growth or success.

At 8 months after a hair transplant yo should be as normal as when you had your original hair there and do whatever you want

There is no need for concern that any of the things you mention would increase the risk of infection or in any other way have an adverse effect on your transplant. Enjoy your hiking and camping. :)