@Logan We often camp where there are few trees, so we fall back on cots in a tent. Are there any reliable ways to attach a hammock to a vehicle on one end and… use some other anchor for the other?
Oh, before I forget. On the topic of bad backs, I totally forgot about this earlier. There is another type of hammock you should look into, its called a "bridge hammock". Its supposed to be the flattest laying hammock out there. It uses aluminum poles, catenary cut fabric, and geometry to keep you flat. Think of it as a hybrid between a gathered end hammock (what you likely have now), and the "spreader bar" hammocks you see in backyards.
You can make them, or buy them. Here is one I just found.
Introducing the Banyan Bridge Hammock! Purchase your banyan bridge body hammock here! Explore our color variety and find what is best for you. Click here!
dutchwaregear.com
Yeah, having lived in places with less trees, this could definitely be a problem. I've not researched it much specifically (usually the trees are too close here), but I've heard some of the people discuss ways to do this.
Most of the methods for attaching to a vehicle, revolve around attaching the hammock either to the roof rack, the B/C pillar, or sometimes even through the open windows and around the roof. Most of these are using some sort of wide webbing (2in or so), with something on it to protect the vehicle
Here is someone using the "webbing through the doors and over the roof" method.
I've even heard of some people using stretches of 2x4 (with padding on it so it doesn't damage the vehicle) that are wider than the window opening, and then simply attaching the suspension to the 2x4, and hanging from that (because it cannot fit back through the window). And I've seen some people do the same thing, but pinching the piece of wood between the door and the doorframe by the hinge so that it cannot come through.
These sound viable... but not sure if I'd do some of these on a vehicle I cared about.
With a truck you have the stake pockets to work with, and of course hitch mounted options. But I'd worry about the stake pockets having enough material to work with to support the load (the hang angle is very important here, as its easy to get multiple times your body weight as load on the suspension if your hang angle is too flat).
As for no place to hang from the other side? I've seen some people build tripods, or other hammock stands. But those seem like a lot of work/stuff to carry to make it work.
I did just run across this though. It seems like something like this could work and not take a truck bed full of lumber to work

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EDIT: And found this. This might be up your alley.
The Turtlebug Camper Hammock Stand is a budget-friendly camping hammock stand designed for full-sized (11 foot)camping hammocks. Portable and affordable,
dutchwaregear.com
Disclaimer, I've not tried any of these, because, just haven't had the need.
If it were me, roof rails (with ideally a parallel load, rather than perpendicular) and maybe B pillar would be my first instincts to try. And I'd probably do something like shown in the video for the other end (but may angle it to support the load better), and may experiment with different anchoring options.