My husband and I are very experienced campers but had to change quite a bit once the kiddos came along. We can't exactly do our once-normal 5-10 day backpacking trips in the middle-of-nowhere with a 5 year old, 2 year old and 9 month old! :-)
Our two older kids are old pros at camping. My son (the oldest) could put the tent up by himself before his 3rd birthday! Anyways... taking kids camping is fun. Now we do what you described... car camping. But it's still fun. We have a one-room tent and it's fine. At 18 months, the kids were still in the pack 'n play for camping. It was in the tent. It's also easy to move outside during the day to keep them contained for a few minutes when you need it. We haven't bought one of those portable playyard things but I see them alot at campgrounds. The kids go to bed late because of it being light so late (who the heck decided that IN should be in the Eastern timezone instead of Central... we dont need light at 10pm!!) and they wake up early. We do try to get them to nap in the afternoon but it's hard. Basically they are very tired and don't get anough sleep for 2-3 days but oh well. It's part of camping. :-)
A stroller and pack 'n play are almost a must, IMO. You need a way to contain her for a few minutes because you will have times when you can't watch her. And if she's 'loose' you need to keep an eye on her at all times. A curious toddler can get into much trouble at a campgrounds... being close to a road and other cars, getting too close to fires, etc. I'm super-paranoid about youngsters and fires. We don't even have a campfire when we have a child under 2 that's walking. I've seen too many 1 year olds accidently get burned on the fire or the hot fire grate put down nearby.
We also have a stay-out-of-the-tent rule. Unless it's afternoon naptime, no kids are allowed inside the tent during the day. Trust me. Camping kids are dirt magnets. Never allow shoes in the tent, either. We keep a box of wipes right inside the tent door. The kids sit down on the tarp we have outside tent to take off their shoes and get wiped down - hands, face, arms, feet, whatever - before entering. Baby wipes are also great for cleaning up before meals. Take make meals easier, bring along a feeding seat. The kind that straps onto a normal chair will strap onto a picnic table bence. The ones that clamp onto the table also work, but only certain ones. Some brands won't fit on the thick tops of picnic tables. Expect her to get really dirty and let her explore as much as is safe. Also let her help... even a toddler can bring you small pieces of firewood from the pile or 'help' carry a bucket of water. Above all - have fun! And show her how great it is to be in the outdoors.