If you can hit a Nat Forest campground that works, but check on where you can dump. I will go a night without dumping but that's about it.
I find a campground and get the cheapest site I can find. Generally 30 to 40 bucks. I'm most interested in electric water sites. It is nice to have some comfort on this long multi-day trips. But I do, from my own past, understand the limitations of a pocket book upon occasion. I always have a couple of the light blue six gallon water jugs from Walmart so, if I am going dry a night, I can put enough water in to have a shower and water at the sink and a 2200 watt generator to power up to do so... If you have access to potable water and have a small genset, you pretty much are in business for a day or two.
And a parking lot doesn't cut it for me. If you have to go out to eat, you just ate up the cost savings of any old place. Stouffers Lasagna, a bottle of wine and a good old movie is a good night on the road. Walmarts are also noisy and not for certain safety issues can arise... I live in a small city in Montana and I wouldn't want to stay in my Walmart and its likely about as good as it gets. I got into harvest host early this year and found it wanting from like having six or seven people never contact me back to unavailability and associated frustrations. Most of the "bigger" rv places along the highway usually have a site or two, at least, open and you can find them on short notice while traveling...
Just my opinion. I don't have to stress out, google is your friend, reviews tell the tale and everything is smooth, pretty much for us... Oh, and we have been doing this stuff for 17 years towing something to sleep in on the back... I know how it all works, got camping sites at some of the hardest best places in the country this year, so know how that all works and live in Montana. This is all from lessons learned and lots of experience... But my needs are not necessarily yours, whomever you are so good luck.