thanks for your help.
no, it's not likely the preloader will be the exclusive determinant of the 50k limit.
but is the preloader the route I need to take to do an initial load or do I need to add code somewhere and if so what is the code?
there's no easy answer (other than nothing simple will solve all problems).
you need to test to see what the limit enforcer checks. for an ad, an initial load should be irrelevant, and they should disallow work-arounds.