I've found that it has been very hard for me to fit my ideas to a BIAB style that works. In fact, after many tries, I have never yet gotten even one to work. The flow of the song is never quite what I had in mind.

So what I do is:
1) play the song into RB and record it as audio. If I plan to play more than one instrument, I continue adding tracks until I've done what I can do myself.

2) clean up loose ends with audio editing to get a reasonably cohesive starting point that isn't out of time or out of tune.

3) send this to the audio chord wizard and extract chords & tempo map it. (may not be necessary if I've recorded to a click track)

4) clean up the chords, and embellish

5) At this point the song is sufficiently developed that it has the feel I wanted, and all the specific parts I wanted to play. Then I start adding additional RT instruments, being careful not to introduce any tracks that change the desired fell of the song

(This is one of the reasons why I like RB so much... it shares BIAB's ability to add content, but it lets me establish the feel of the song, then add to it. With BIAB I always feel like I have to change my part to fit the style.)

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0