I've used this pullout too and it seems to work fine for the first few vehicles that get there early...
+1 ... we did the same thing with no issues.
Notes from my journal:
After the turnoff for Copper Mountain, continue on the highway and use one of the pullouts on the south side of the highway just before the highway begins to ascend Fremont Pass. Do not park near the turnoff for the "sea of crap". There are multiple no parking signs. The rain, which had begun around Frisco, was steady and light. Oh well. We donned our raingear and walked across the road (to the north) ascending slightly in elevation. Behind the two large rocks (a bit above and behind the "no parking" signs), you will find an old abandoned jeep road. We followed this for quite awhile as it zigged and zagged its way up the hillside. Specific directions from here would be pointless. We followed this road, along with some game trails, bushwacked a little and ended up on a high ridge and then followed that ridge (in the clouds and rain) to the summit. The rain continued, more heavily at times, the entire way to the top. The rocks near the summit were wet and puddled up which made footing slippery and balance questionable. There was a summit cairn, but no register. The views ... well, there were no views. We saw no other climbers (hahahahahahah) and we did not stay long. The rain stopped for a bit on our descent and we were able to follow game trails/jeep tracks all the way back down to the jeep road we had started out following in the morning. By the time we reached the truck, it was raining pretty good and continued all the way to Denver.