quilterj --- about the sleeve: 1) If too wide, take it in lengthwise 2) If not long enough to turn under perhaps you could add wide ribbon or bias tape to the end. Then you could add velcro or two snaps which would be hidden when turned under the board. 3} When I did not have enough fabric length on one board, I added contrasting material to both ends so the result appeared to have been planned...Hehehe
quilterj --- about stitching the tie to the end of the bow tucks bag: I stitch it on by using a rectangle -- across, down x stitches, across on bottom, up x stitches and back tack to secure the ends. With this technique, I've not had any difficulty with the ties becoming undone.
Good luck:-)