That is excellent idea. It will be very useful too in a quaranteen tank. As I saw here a picture of a guy who made a square QT, he can very easily add 60cm high 6mm glass(thats the minimum) all round it, and if the pond is too long, Aluminium frame can be added on the sight and middle,(to break the glass in smaller length sections) and siliconed, after being bolted/ fixed to the walls of the pond. If you want more hight you will need 10mm glass.
It will be very useful to observe the fish for diseases.