I went into all this with Here's Your Live Arranger
I could do it all right now with Reaper, I just set a certain midi chord input to play that chord section of the RealTrack source file, round robin to play the same chord but a different section each time.

There's your $100USD virtual instrument X how many RealTracks you have:

Code
file1 = "E:|\bb\\RealTracks\\Guitar, 12-String Acoustic, Strumming Ev 120\\AG1141.wma"

wma_source1 = reaper.PCM_Source_CreateFromFile(file1)

track1 = reaper.CF_CreatePreview(wma_source1)

reaper.CF_Preview_SetValue(track1, "D_VOLUME", 1)

reaper.CF_Preview_SetValue(track1, "D_POSITION", 4)

reaper.CF_Preview_SetValue(track1, "D_PITCH", 2)

reaper.CF_Preview_SetValue(track1, "D_PLAYRATE", 1)

reaper.CF_Preview_SetValue(track1, "B_PPITCH", 1)

reaper.CF_Preview_Play(track1)

retval, current_pos  = reaper.CF_Preview_GetValue(track1, "D_POSITION")

This is where you also need to record on the same guitar, same levels but different patterns/styles so it will match tone when changing to another pattern during a song, if they are Direct Input, you can use the same FX on them.