TL:DR Yes, 2 people, unless you’re one of those “brings the kitchen sink” types.
Here’s what I was able to fit into the “trunk” alone:
- Two 10×8 Tarps
- One 10×8 Tent
- One 7×4 Tent*
- Two Pillows
- Two Fleece Sleeping Bags
- Backpack with
- Real tent stakes
- Hammer
- Fishing Tackle + Rod
- Paracord
- Multitools
- Fire starters
- Water bottles
- Metal cups
- other miscellaneous basic survival gear
*the smaller tent fits into the larger tent for additional heat retention in case it’s 10°F colder than you packed for, or it’s too hot for the larger tent with tarps on and under it and you just need a bug-free space to sleep.
That’s pretty much all you’ll need for a typical trip at a state park where running water and fire pits with grills are provided, leaving the back seat available (folded up or down) for clothes and a cooler and whatever you choose to sleep on.
As far as sleeping IN the prius c. No. Regular Prius it’s very easy but the trunk and folded seats aren’t level in the c, and even then, their total combined length is insufficient for even someone as short as me. You can sleep in it as well as you can sleep in any car with reclining front seats, but you’re not getting a bed like you could with larger hatchbacks.