Although the official limit is 1 night at Horseshoe Meadow, I have not had it enforced. Of course, that depends on how busy it is and if you are a responsible/polite camper.
I have spent 3 consecutive nights at HM without a issue. But, the campground was no where near to being full and I didn't have a lot of gear spread out all over the place.
So if you need to spend a extra night, and there is space, it should be ok.
