Maybe I'm naive, but I'm thinking being parked on somebody's private property is probably more safe than BLM or boondocking areas.
I'd definitely say so...a friend stayed on BLM living an at least partially nomadic lifestyle in her T@B - On at last one occasion a person walked by her camp and was acting very strangely. Not really physicall threatening, but a little bit. It could have been with violent intent, or intent to rob.
She being an older (but not old) woman, had to display a firearm (not brandish, or draw...simply to display it by pulling back a shirt showing its presence) to convince a ner-do-well that it would be wise to move on. It turned out well, but BLM is not 'safe' -- you do need to take accountability and maintain situational awareness at a higher level then you would in 'safe' surroundings.
I sincerely doubt anything like that would ever happen in a state park, or any gated campground. But even there, I've seen things not go very well, in fact it was in our loop on our trip just a few weeks ago to a State Park we've visited probably 50 times.
HipCamp or any private property clearly would fall somewhere in between. You're not completely alone, but you don't have security either. But you are at obscured in the visual noise around a farm, or hidden behind some trees in some ones back 40. So you're somewhere between the relative safety of a campground and the wild-west of BLM.
I don't think Hipcamp is a bad idea - in fact, i'll LIKELY use it once I get my new CI. There are a couple hosts very close to a place I need to go somewhat routinely as part of my familial duties. I just wish there was a little more transparency on the locations of the sites before you went through the booking process.
I want to see the neighborhood. The automobile scrap yard that is 1/4 mile away, or the shopping plaza with a liquor store next to a trashed out mobile home. Small towns are not immune from crime. A little areal recon in advance if you will. It would be unforunate to plan a night stop to get to the area and immediately think "Oh brother...what did I get myself in too"
I hope the reviews improve over time..but the spots I looked at were too new to have anything too helpful written yet.
This still reminds me a little bit of Craigslist...