I'd worry more about the tent. I grew up in a laundry and there is a lot of lore about dry cleaning and down. Back then, we used carbon tetracloride as the solvent which was pretty harsh, but was still easier on delicates than water/detergent. Now days, dry cleaning can mean several things including spot cleaning the bag's shell. Chemicals can range all the way to "liquid carbon dioxide" depending on the laundry's equipment.
I wouldn't worry about the down bag so much. Down is very tough stuff. I wash my down bags with regular laundry detergent, throw them in the dryer til dry and fluffy and that's it. One of my favorite bags was bought in 1984 and is still my favorite, probably dry cleaned along the way at some point. Most of the time I hang and hand wash the shell using Dawn and warm water/sponge...its quick.
Anyway, if you know the dry cleaners your friend used, call them and ask. They probably get down comforters all the time and know exactly what to do with them. It's likely the new processes are safe.
The tent....different story. Might have to set it up and hit it with your water hose. Still, today's dry cleaning is much gentler and the launderers usually know what they can clean and what they can't.