I have only hunted one season here in BC but I did take a sheep and a goat. Here is my take:
If this is a super rare tag and you might only hunt goats a couple of times then get a spotter. You want to make this hunt count and you don't want anything holding you back, no what-ifs. Like mentioned above, a spotter will significantly help your hunt. Buy a decent spotter used on the classifieds and sell if after the season if needed. Seems like you will even be able to get your hands on one for free.
On my goat hunt, I watched my son's billy at 340 yds and no way was I sexing it correctly with just bino's. With the spotter I could see his balls, 100% confirmed. When the billy bedded we were able to make the climb and be certain we were headed after an animal we wanted to kill.
Having said that, I would do a goat hunt without a spotter. I can hunt goats every year within a 45 min drive of my house so I don't have the same pressure to make it happen. It might mean I stalk a few goats that I don't end up killing but I can deal with that. Also, horn size is just not important to me right now. A HUGE goat and a small one are barely distinguishable. It's not like moose/elk/deer where mature animals are drastically more impressive. So I don't need a spotter to find a "trophy".