Coarse will be small pebbles. You can easily put all the cuttings in a single bucket. I just tie 5 together with soft cord or with twist-tie material (plastic coated wire found in any big-box store such as Lowe's). I will tie near the bottom and then about 2-3's up so that the bundle will be nice and stable. I would have about 3-4" of perlite on the bottom, put that bundle onto the perlite (you can tilt the bundle so that it rests on the lip of the bucket) and then add another 3-4" over the bases. That's it. Just keep the bucket in a warmish place, above 50F. It does not matter whether it is dark or not. All I do is mist those tiny, terminal leaves every few weeks. If you have some air movement that's better but not critical. I have my buckets in my "Everything Else" greenhouse and there are always fans running. Being in a greenhouse, my cuttings gets lots of bright light and even direct sunlight this time of year won't hurt them a bit. If a bit of moisture gets into the perlite, no big deal. If a lot of water gets in and makes the perlite really moist, just remove everything, re-do with fresh perlite, and away you go. Don't throw the wet perlite away. Use it in potting media or let it dry out and its ready to go again.
Those plants had an interesting journey. You would have gotten them three days earlier if your CA Dept. of Agriculture had not confiscated them when they arrived at your post office.
A crappy dog sniffed them out. My tax dollars at work.
I am now considering NOT shipping anything to CA other than epiphytic plants. I have shipped to CA for over five years and now in the last two months, I have had two boxes of plants intercepted. The first was a box of two, 3' fiddle leaf ficus plants. They destroyed these beautiful, healthy plants, claiming they found some dirt there. I don't use dirt to grow my fiddles, only peat, sphagnum, and perlite. The agent could not have cared less when I told her this. To her, it was dirt, and that was that. Naturally, I refunded everything to that customer and took the hit. The agent I spoke to about the plumeria was actually very nice to me. He was out of the Sacramento office. He said those fiddles were supposed to have been returned to me since they were shipped Priority Mail. He did not have a clue why the agent (in S. CA) would destroy the plants rather than ship them back to me.