All it takes to eliminate the possibility is a phone call. If you are going to do some unusual ops in and around YMNG or any other airport that has high volumes of training, particularly foreign students.
Ring up, talk to the CP, CFI or even the duty instructor. They will put in a ground stop for the time you want......no problem. At the very least, the duty instructor can brief the students in a manner that they will understand of what's going to happen.
Most students, especially foreign students can not assimilate a call for non standard ops. Just saying on the radio in a few minutes you will be doing this and that simply doesn't compute. What they don't understand they simply dump from the consciousness.
There is no point whinging about poor English skills, that's the reality, always has been, always will be.