The dome with the thermostat is your best option and will ultimately be the easiest. It sits on top of the cage bars of the roof pointing down. You do not need a guard if you do this because the cage bars serve that purpose.
With the dome you may or may not need anything to cover the back or one side of the cage. I'd start with that. The thermostat will let you see exactly where the temperature is in the cage. Then you will be able to see if any further steps are needed.
If you do need coroplast, you can get it later. (It is called coroplast, not chloroplast)
This photo shows a similar cage to yours with a dome on top.
here with my Mecki-- born 2/12/19
Last edited by Mecki; 04-18-2019 at 02:34 PM.