I understand that the "whopping" part is not your opinion, but why bother?
Worst case scenario, you have to email the executable and instruct the client to download the RTE from the web (if you have somewhere without a web connection, you might as well send them a CD).
NI presumably puts a lot of design and testing into the development of the RTE and installers for each version and attempting to work around that with each new version sounds like a lot of work for little gain (unless you wanted to be able to run something without installing, which is not your case).
I doubt you will find many people who can give you a definitive answer, as this is clearly unusual usage.