wrap mp3s still bookmarkable

Personally, I do anything like that with Audacity. It might take a bit longer but it always gets the results and I use a Rockboxed Sansa Clip+ too.

It's just a case of importing the files one after another. There are plenty of tutorials on popular websites.

However, Audacity does decode and then re-encode your files so there will be some loss in quality which you don't get with mp3wrap. I guess this doesn't really solve your problem unless you have the files available in a lossless format.

Are the individual mp3s bookmarkable before you wrap them? I seem to recall that mp4box has a hint function which works with audio files. I think I used that before when I had large audio files that wouldn't scroll properly. Maybe try that? It's in the repositories as part of the gpac package.

Found out how to do it with ffmpeg.
ffmpeg -i "concat:file1.mp3|file2.mp3" -acodec copy output.mp3
just use the tab key to auto-complete the file names but I think you need to do that before putting it in with "concat: and | ". Otherwise, the tab autocompletion will not work.

I tested the completed file with rockbox firmware on sansa clip plus and it works with being able to set a bookmark.