Mississippi Road Trip: Packing light

We're heading out for a two-and-half-week road-trip. It'd be easy to bring everything—but the kitchen sink. Lots of toys and books for the kids to play with in the car. My daughter's gazillion sundresses, which would certainly be appropriate for the Midwest's hot summers. Unfortunately, we can't!

We're flying to our starting point, St. Paul/Minneapolis, and we must keep our baggage fees low--since we're doing this trip on a budget of $150 a day. We're flying Northwest Airlines and they charge $15 for the first bag and $25 for the second (scandalous!), so I'm hoping I can pack everything for our family of into four small carry-on bags and one big bag that we'll check. This keeps our costs down to $15. Ideally, these bags will come with us onto the plane.

Here's the packing list that each family member is following:

• Two pairs shoes: one pair tennis shoes, one pair flip-flops or sandals
• One pair pants: Wonder if we should even bother since it'll be baking hot?
• Shorts (one pair for girls; two pairs for boys)
  
• Three tops
• One dress for girls (I might allow my daughter to bring a second one!)
  
• One sweater or light coat
  
• Five pairs underwear
• Three pairs socks
• One pair pajamas
  

We'll obviously be doing some laundry in the hotel sink along the way, but I'm packing dark-colored clothing that won't show the dirt.