So when I used this method last summer it was on two species plants that I got bare root with no good roots. I first put the plants on a bed of sphagnum moss in a ziplock bag and after they grew enough roots to plant I planted them in a clay pot and sphagnum moss. Then after I potted them I put a ziplock bag over the pot until they started growing well. I grow almost all my plants in sphagnum moss and clay pots so if you usually use a bark mix in a plastic pot that will be fine too if the plant has enough roots to be planted normally.
For an example I am using a sandwich size ziplock bag. You will have to use a bigger one of course. This is how I cut the holes in the bag. This is what it looks like. Like I said before with a bigger bag you will cut more holes in the sides.
Then soak the moss and squeeze most of the water out so it is moist but not sopping wet. I don't have a bare root plant right now to show you with but just place the plant in the bag. I would probably put the roots down sitting on the moss. You can also soak the moss in a little SuperThrive or KLN. That is what I do. Then hang the bag in a warm spot that has light but not as bright as when you grow a healthy plant. You can open the top of the bag a little bit if you need more air flow.
Then after the plant grew enough roots I planted it and put a bag over the plant for extra humidity until I thought it was healthy to grow by itself. I took a ziplock bag and cut the corners like before but since my plant was small I didn't cut any holes in the sides. If you need to you can. I also would take it off for a few hours if it was too wet. You don't want it to be too warm in the bags to where you would cook the plant. You are just using the bag like a little greenhouse. This is how I put it over the pot.
Make sure the holes in the bag are open and are not collapsed shut. Like this.
You can close the bottom of the bag around the pot as tight as you want or open it a little if you need more air flow. Make sure you keep the moss moist. Watch it closely and if you think it is too wet or growing mold give it more air flow.
One of the plants I used this method on is doing great. It is a Sophronitis acuensis. It took about 6 weeks in the bag bare root for it to grow enough roots to be planted. Since then it has grown 15 new growths! The other plant took longer so I don't know how long it will take for your plant. My plants had psuedobulbs to support them through that time though. As long as you can keep the plant from loosing its leaves it should have a fighting chance. You also have a couple ok roots so hopefully they will take off in the humid environment. You also have hybrid vigor on your side! I hope it works for you and if you have any more questions I will try to answer them. Good luck!
Wynn Dee