I can understand the effort you would have put at that time, i too almost daily before/after officer hours visit them.
Yes, this .25 cm piece of wood technique seems workable. Will do it on the coming weekend.
Today morning i searched auto shops in the "Chaah Sultan" that is one of the biggest auto markets in Rawalpindi/Islamabad. But surprisingly i couldn't find "Rust Converter" there. They even didn't knew about it.
I will visit some good automotive paint shops in the city and definitely buy a good rust converter. I have strictly asked the painter not to do any kind of work unless this rust converter is applied thoroughly. He seemed happy to get some time to work on other cars in the meanwhile
Cavity wax is a very good idea and highly practical at this time. I don't mind if even a week or more is spent in these protective activities.
And thankyou so very much @omersiddiqui5482 bro for your valuable guidance. This really helps a lot bro. Stay blessed.