What are the dimensions on that? The width looks very small. Screen top will give you troubles trying to reach optimal humidity levels also. It appears she has all the essentials at the moment....If you are looking for any advice I would suggest considering:
1.) ditch the red light - those can actually be seen by reptiles and disrupt their night/day cycle... Tegus don't need night time heat as long as it stays above ~68-70.
2.) seal off as much of the screen top as possible to help hold humidity... regular plastic wrap can get the job done there as long as not touching any heat elements.
3.) work on trying to get her a larger enclosure... she would surely appreciate a little more space. Grow tents are a great option if you are on a budget... aim for 8x4x4
Body and tail seem to have their own shed cycles from my experience, it doesn't mean you are doing anything wrong as long as there are not multiple layers or cracking or anything occurring, it's fine. It'll come off when it's ready