It is not ideal and gives some challenges, but I can spray baste a queen sized quilt on my queen sized bed, it would be easier if I didn't have a four-poster. I have a small house and it is my largest available workspace. Back before my husband moved in I had a bigger dining room table that was close to twin bed size with the leaves in, or I could move the furniture around. Don't have those options now.
I have a roll of heavy brown craft paper. I cut three pieces off to well cover the bed and use those through the year until they get too worn out, they are coiled around the roll of paper when not in use. I strip the bed and layout out the paper. Typically the width of the quilt will fit the length of the bed, so you do in sections as usual, starting from the "middle" and going carefully up one way, then when it is secure you go back down the other way, flip and repeat.
Yes, I'd rather go use a big table at the library or a conference room or somewhere. As I'm doing it I'm telling myself that this is better than being down on the floor.
For twin sized quilts, I think pool noodles are still an option.
https://www.youtube.com/watch?v=EpmWfZdxGSI
They are currently in our currently open dollar stores in the Seattle area.