I just found an easy way to do missions where you need to tag a number of animals while playing the mission 'tag 10 beavers in 3 hours with a handgun'.
When you're in a mission, you can press start and go back to the outpost. Re-start the mission (by walking to the area which the hunt was in), and the tags you made are still completed! Also, it will reset any time limit and the warnings. With this method, I managed to tag the 10 beavers in about 15 minutes, with 3 restarts of this level