not really answering your question but ill try explain where i am coming from.
I also am thinking about going to the states next summer to complete my training after graduation. so this summer i wanted to get all my paperwork out of the way.
rung up a few flying schools, priced the cheapest and went with that. they didnt charge me a membership fee but some do, and they could do the RT exam in house.
I now have done 5 of the exams. the remaining two booked in for next wednesday. a medical booked in for saturday and my RT practical booked in for next friday.
So it is possible to do it. Just get calling schools. they are all usually very helpful.