Although after step 5 and before you can move onto step 6 you need to confirm the HC12s will give you the range you want, its pointless planning the project until you know the chosen equipment will work (in a forest).
According to data sheet, the range of HC12 is about 1.7 km. Now, comes the question of obstacles; there are always obstacles in the path of radio signals, and those obstacles are to be defeated this way or that way to achieve the target. The Op has to go at the real site with equipment that work; therefore, it is a good opportunity for him to make his whole network operational in the personal Lab.
Thank you for the remarks.