please let us know hows your iguana is getting on, i couldn't believe the pictures when i saw them, good on you for taking her in and caring for her, world needs more people like you!
I used to do a lot of rescue work when I was younger. I'm not an expert by any means. I did pretty much what your doing. Lots of baths, and let them eat whatever at first. Slowly try and introduce more foods. let them get their strength up before you do anything drastic. Sometimes the color of the food made a difference. I had some that would be intrigued by a new bright color, or would be willing to try a new food the same color as their favorite. And I found all my iguanas would eat better if their salads had a wide variety of colors. It's been like 10 years since I had iguanas, but I think I read that color is very important to them. Lots of different colors are exciting.
Try asking your doctor for silverdine ointment. It is especially for burns, and can be safely used on reptiles. DO NOT use it on or in the eyes. It is for external use only. Great stuff.