I had Unit 13 Colorado in 2006. Same feelings of euphoria, trepidation, etc. I knew I was going to DIY. Scouted over the summer, had my spotting scope on the billy that I wanted two days before season after looking over hundreds of goats (likely the same ones more than once).
I ended up shooting my second choice after spending 4 days watching the one I wanted but knowing that although I could have easily shot it, I could not have recovered it or it would have fallen hundreds of feet before it touched anything. He never moved from his sanctuary all summer and during hunting season.
If you have the time, spend it scouting and enjoy the whole experience. The shot was anticlimactic. It was the whole experience.
You will not need a guide if you are a competent backpacker. Just spend time scouting the whole unit. Make sure that the animal is recoverable before squeezing the trigger. One last piece of advice, draw an imaginary line from the base of its tail to the base of the ear, and a second imaginary line running at a 90 degree angle to the first line, bisecting the back of the front knee. Wherever the two lines intersect, shoot it there. You will likely break one or both shoulders and the spine, dropping it in its tracks.
Good luck and have fun.
WyMo