Charlie,
That sounds like George Harrison in his "Indian days" and so I like the vibe, man!
it needs something 'more' to complete it but everything I have tried for the last few days detracts rather than builds the song.
I know the feeling!
I reached this point recently on one song and wondered how to improve it. I then bounced the vocal,which was recorded in my DAW, to a "wav" file and imported that as the audio track into BIAB.
SO now the song is in BIAB and I now can change the RT's and Real Drums whilst keeping tempo etc the same. I then experimented with RTs to make them match the vocals instead of the other way round. I kept the original file saved as "song" orig and saved the new working file as "song" new.
Care has to be taken that both line up and the number of bars in the vocal wav and BIAB song are the same. I did this by adding a bar at the beginning of the BIAB song, and the vocal, so I knew they lined up and also set the value in the 1st box of the import dialogue to 1.
Start here if all was recorded in BIAB !! My song was 4/4 and I even tried 3/4 tracks which added a "weird" but interesting feeling especially mixed with the 4/4 RTs. In fact I tried everything, Sw vs even, double and half time, until "that moment" of "OH YEH" arrived which took some time but was definitely worth it. I then dragged and dropped the new tracks back into the DAW and spliced and diced all the tracks. Actually in my example I got rid of all the original tracks and the song became SO different, but the same....if you see what I mean. I will post both versions of mine later so you can hear the difference.
I found this method worked better than being stuck in the original idea as I could always revert and start again! Working against/with the vocal in place certainly made things a bit easier. One could always redo the vocal at the end if necessary.
This would also work in Real Band but I struggle with that

and so I use BIAB and then Cubase SX but any DAW will do.
I am away from my DAW at the moment so PM me or continue here and I will try and answer any questions by referring to the file and not from my old man memory!
Re the George Harrison vibe in his Indian days maybe, if the RT solo has the underlying midi file use that and try a sitar midi patch in a VSTi, soundfont or something like Coyote.
I hope you understand what I have said.
I did enjoy this version tho'
Alyn