Depending on what your son is like socially, it might be easier to find a smaller yeshiva where he would feel more comfortable as well as work along with you financially and academically while he adjusts to a school setting. Possibly he can do work in the school (kitchen help?) or tutoring a younger child if hes good in math or another particular area to help cover the cost of tuition. Depending on the area, you may be able to find someone for him to board at (also for exchange of a service if applicable). You didnt mention if the reading difficulty is in general or only with English or kriah or the level of difficulty but if necessary, it’s probably easier to work on before hes in a completely new environment.
I’m not sure this fits your situation specifically but I believe there is a Dr. Rosenshein (?) who helps to place children who need schools, but I dont have contact info.
Much Hatzlacha