If you are serious about it, (I assume you are!
Not trying to heckle), you should check out the book at this link-
the link itself has some useful but muted info, but the book is loaded and excellent. Author is a super cool guy, really good guy who knows his stuff:
Book on RMNP Fishing
You may be able to buy this book at Kirk's, shocked if they don't have it.
Also, here is a link to a couple posts I've made on another forum re: Big Thompson River and RMNP:
There are many hikes and lakes and streams/rivers to fish in RMNP, it's an amazingly beautiful spot. Good luck to you!