In reply to Robin Woodward:
Not exactly in your desired area but the Braemar campsite has excellent boot and garment drying facilities.
I seem to remember the Aviemore one opposite Glenmore did but they were unusually snotty with us last time we stayed and demanded on inspecting my VW T5 to "check" it was a camper, the fact its got a pop top in it and rear windows should have given it away.....