Phwew! Makes me tired just thinking about your situation
Could you do something like this–gather a few laundry baskets, a few carpet squares–anything that is stackable and easily taken out and put back by your kiddos. Our first graders love to sit in laundry baskets. Carpet squares fit nicely under tables or in small open spaces.
One of our teachers also has a couple of those kdg nap maps that the kids love to stretch out on while they read. Don’t give up–You can find simple ways that won’t cause you a lot of effort!!

Even though we have space in our classroom, many of my students prefer sitting at their desks. Others enjoy sitting under their desks. Neither option take up available space, leaving what’s left over for the remaining students. I have a couple of collapsible stools they can set up anywhere, except where I am conferring with my individual or small group.

It’s more about not being told where to sit than offering amazing spaces. Flow with it…it’s all good…

Thanks for the encouragement to continue. Here’s what we’ve done. We’ve marked with a masking tape x what spaces are available, under the tables, on the floors and are having the kids go one by one to choose a space. It takes forever! But we hope that the time will shorten as we practice. (yes, we’ve already done the teacher seating them. Now the choice seems to confuse them!)

Have you considered removing some of your tables? We typically have “table seats and spaces” for 1/2 of our students. The spaces aren’t assigned. This way students can choose to sit at tables if they wish, or in the alternative spaces. We use lapboards and clipboards for writing.
I know it sounds like it would be crazy, yet I wouldn’t do it any other way. We have done it this way for years. Here is a whole section on our website devoted to this topic: https://www.thedailycafe.com/classroom-design/classroom/student-spaces