The group of Camillo La Mesa at Sapienza University of Rome has several results in similar topics. Please check the publications of the group maybe you can find what you are looking for
The area you have marked is not a microemulsion; it is a molecular solution and as you approach the two-phase area; the solution is affected by the plait point structures. Although the temporary concentration fluctuations may well be of colloidal size, their life span is only of the order of small, small fractions of a second.
If you want a microemulsion, there must be surfactants involved, and the association structures now last for seconds and can be used for solubilization purposes.
There is a simple chapter in Fanum's book on microemulsions, written by me and Pat Aikens, which gives you an overview on the phases involved in microemulsions.