I don't know what you mean by "SUV camping", but bear in mind that in February, much of the US is under winter weather. Many public and private campgrounds are closed. Sleeping in your vehicle could be VERY uncomfortable due to outside temperatures - even in the South. Same with "Stealth camping", which I assume you mean pulling over someplace and staying overnight in a hidden spot. You can't just pull over anywhere in the US to do that. You may be woken in the middle of the night and asked to move on, or even looking at the wrong end of somebody's shotgun, if you choose someone's private property. There ARE places in the US for dispersed camping, but most of them (on national forest property) are located in or west of the Rockies. Really, your best bet are cheap motels.

As for "must-sees and must-dos", the one thing we believe and stress around here is that your trip should be tailored to what YOU like. You've given us some good starts. So, that said....

You'll find Civil War sites (Manassas, Fredericksburg, Antietam, Gettysburg) in the DC area as well as Shiloh in TN and another in Vicksburg, MS. In VA and points south, you can find the Blue Ridge Mountain Highway as well as Shenandoah National Park's Skyline Drive.

Do you have a road atlas of the US? If not, you should get one. This site, Amazon, and more have the Rand McNally, which my husband and I consider "the best".

Donna