To me it seems more that you're asking for a way to quickly bounce/merge multiple clips into a single one, that's it ?
I tried your trick Jason, but it only copies the selection somewhere else, it is not like rendering in order to get something else, a new single file.
But maybe i'm biased (as i really would like a lot such a thing since months !), or maybe also i didn't understand you
If it is the case, enzymeX, such a feature has been requested several times since the early days of Reaper, and even recently about merging also midi clips.
I made ap ost two days ago gathering some infos & useres suggestions :
http://www.cockos.com/forum/showpost...98&postcount=5
I hope it is in the "todo" list