Many thanks for your responses.
Void, your external monitor is probably going to be the most reliable and future-proof method, but it's also going to be the most work! I may get around to doing it this way, one day.
DoteDote, yeah, I was speculating along those lines myself. But what I forgot to mention is that this needs to work across various instances of the object.
Innula, I've tested your suggestion a few dozen times now, and it's worked every time, so this is the way I'll go for now. Mind you, it has been pretty lag-free here so far.