However, the Sxs folder is over 200 megabytes, I could save some time provisioning the machine if I didn't have to include the whole folder.
This is an example of what you developers refer to as "premature optimization." 200 megabytes is small enough that you shouldn't be concerned with it for the purposes of data transfer or provisioning. If it's a problem, then you actually have a much bigger problem (like trying to provision a server over a dial-up connection, or onto a 15 year old hard drive).
You'll spend a lot more time figuring this out than you'll save by doing so. And in the end, trying to prune down your SxS folder is a bad idea to begin with, as it exists to allow compatibility with multiple versions of libraries (dlls), applications and system processes.
In short, don't do this, and in fact, you should expect your server's SxS folder to be a lot bigger than 200 MB, once all is said and done.