As I see it, there may be two reasons why a flight school would not want to own an aircraft directly: capital investment and unscheduled maintenance.
The latter has been discussed here at length and it seems that there are a few organisations who will take on their share of the unscheduled maintenance for a lower lease back rate.
Capital investment seems to be something that contributers here are prepared to do and that the schools would rather not.
On this basis how about approaching a school with the offer to finance (in part or full) an aircraft for them in return for 'cost price' rental and pro-rata share of the unscheduled maintenance ?
In this way you can separate yourself from the majority of the unscheduled whilst keeping the ability to fly at a cheap rate. If you document the finance correctly you can also keep a first calaim over the aircraft in the case that the school goes bust.