We stayed on the east (south) side, aka Velo De Novia. Keep in mind that there is a very similar place directly on the other side of the river and so the reviews are a mix of both places.
Parked for the day and did the waterfall walk, which is worthwhile. Approx 30 MXN pp to enter the area which gives you access to the falls path for one day only.
We parked in the main lot, closest to the walk entrance. The parking guy said we could park overnight - they never collected any money so it was free for us. The lot is very sloped but we were able to make it flat with 4 plastic jacks.
Seems safe although there were a few vans arriving or leaving during the night.
Place: El Chiflon
Visited: July 21st, 2016
Location: 16.18694, -92.27588