i stayed in the car park at the ben nevis ski resort in february this year...there were no camping signs up,but i asked one of the resort staff if he knew anywhere i could park up,he just pointed to the bottom end of the car park and said ,'nobody will bother you here,the signs are up just to discourage large amounts of campers turning up and turning the place into a camp site and staying for days on end...we were the only van parked up,and no one bothered us at all...the following day we left the van parked up where we had been all night and had a ride up the ski lift with our dogs,....we loved it and when the snow returns this winter we'll be there again..
we also stayed in the car park at the cairngorns ski resort,again nobody bothered us...there was about 2 foot of snow down and the wind got up to about force 6-7,but for me thats all part of the fun.
the cairngorn car park near the ski lifts is split level,so we camped on the bottom level....the car parks were full up during the day because there were so many skiing,so its best to turn up late on when they are all going back to their hotels....