It still is cold, up here and can freeze any morning of the year and does. If I'm photographing from the road and I need to camp and I think the weather will hold for a night or two, I just bivy under the stars - and almost always by myslef (do you know how hard it is to find a woman who's into camping like that, and going like you-know-what all the time looking for animals - its very, very difficult)!
If it's going to rain or snow, I just put up a two man (good quality) tent. I usually never camp in the parks, I hate to camp around a bunch of people, and then have to pay for it on top of that. There are times when I just kick the seat back in my toyota tacoma and sleep in the cab, or streach out in the back. . .
Camping allows you to make better use of your time, especially in the late spring through fall when there's 14-16 hrs of light. Take a chair, a small stove, or a portable bbq, an ice chest with some food, a tarp or two, a small shovel and bucket, first aid kit, some reading material, a pile of energy and nature bars, plenty of water, some apples and take off. If your driving a big rig or sleeping in a rv, you will need to make reservations if your coming to the national park system, they are almost always booked!
I'd be glad to help anyone with info if they ever come up this way (Montana). Take care, Tony