Parking Ruapehu Round the Mountain Track

I thinking of doing Tongariro and the Ruapehu Round the Mountain track again, what are the options for parking these days? I can't seem to find any recent info, but from what I recall hearing parking is very much restricted around Whakapapa, and they encouraging taking the bus/shuttles, which is fine if doing the day great walk, but a big hassle for longer where timings won't be exact. I guess there's other options for longer term parking, but how secure?