I travelled Jan - Sept, Dallas - LA - Inuvik - Alaska - Vancouver. Go for it. I was surprised at how interesting North America can be.
My policy on guidebooks is not to let them totally rule my route. Remember too, if camping that you can very well find cheap and sometimes free campsites that might not be in a guidebook. (Other times, like in California campsites might be in the $16-30 range !!) Also you can try camping for free by just kinda hiding a bit off the road. It's a bit spooky when you try it first, but confidence grows with practise.
I was travelling when it was still a bit cold even in the South West in January. A point to note is that elevation plays an important part in road conditions in NA. You might be all nice and warm one minute. The road then goes up to say 7,000 feet and stays on a high plateau for ages - any you might even be surrounded by snow! Some books may not have elevation info. Of course you might not need it in the summer.
If your route coincides with mine (outlined above) you might look at my site http://www.yourmanontheroad.com
(it'll be going down though in a week or two - no money left!!!
"Because I'm not young enough to know everything!" Oscar Wilde
\"Because I\'m not young enough to know everything!\" Oscar Wilde