Yeah, unfortunately, those mini CDRs only hold 200MB.

I did a quick google on "photo portable dvd burner" and it came up with a couple products made by Delkin and Microsolutions. A 4.7GB DVD would definitely be able to handle those 5MP pictures easily.

The best was the Delkin DVD Burnaway. Even though it can only run on rechargeable/AC it has a car charger and backup rechargeable battery as extra cost accessories. Okay it's MSRP $399 but you don't seem to have many options considering your requirements.
http://www.delkin.com/delkin_products_burnaway_dvd.html

Maybe this and those two accessories would work for you. Hopefully, you'll be near a vehicle with a cigarette lighter adapter often enough so you can recharge both batts when you need to. Unfortunately, camels don't have that feature.

Cheapest, I quickly found online was $349 for the burner. Never heard of the company though. You may find other places that sell it. I saw buydig.com for $379. Read good things about buydig.
http://www.mydigitaldiscount.com/s.n...ategory.470/.f
http://www.buydig.com/shop/product.aspx?sku=DLKDVDBA