My first BJD was actually a 6" tiny (BBB Elfkin) and yeah, I also hand-sew, so now that I have a lot of bigger dolls it's like "gaaaah hugelongseams, make it stoppp!!" I've got a Little Dal which is very similar dimensions to the one you have, paladinari, but I customed her onto a Kelly body right away and then later onto the 11cm Obitsu body, so Kelly clothes are the way to go for her. They still fit the Obitsu body although skirts look shorter (the Obitsu legs are longer) and there is often a lot of room in the shoulders (Kelly's upper chest/shoulders has more to it).
Practice is what does it, and I've been into miniatures and dolls of all sizes for so long, for me it's so much easier to dress a tiny than a big doll. Some of my big dolls have rather complex outfits, though. XD And yes, practice for sewing for tinies is also good! :3 "Practice makes... more practice" is how I put it. XD