Palouse falls camping

I'm making a trip down to Utah in August and I plan on cutting through WA (coming from Vancouver). I want to stop at Palouse falls for a night. Is there any areas I can drive up to that's close to the falls, to camp out? preferably not an expensive campsite like KOA or something. I'll be in a RTT

 

The 'park' itself has maybe a half dozen sites right at the falls for about $12 a night. However they fill up quick. I've camped there before but I've also camped up the road for free. When you are driving in, maybe about a half mile from the proper parking lot (so on the left when you are driving back out) there is a large grass area with a dirt road, drive to the edge...there was a rock fire rim when I was last there

There isn't anything close by. The closet store/restaurant/gas is an hour away

The dropped pin is the free dispersed camping spot I'm referring to
https://imgur.com/Fzm3gDh