I use the big tables at our church. (I'm also employed there.) You could contact the church office and ask if they have a meeting room or fellowship hall that you could use for an hour or so during their regular hours.
Speaking as a church secretary - we'd be just fine with that! =)
I've never been comfortable basting on a floor/carpet. I've been using the table at our church even before I worked there. =)
Good Luck!
Donna Mc