Dwight,
Funny you should ask this. I had a test game Saturday night for a new league I am starting in January. It will have a 20 max (10/table). I was expecting 9 players but word spread and I ended up with 12. I would have had 13 but one player I thought was coming didn't show. I wasn't prepared for 12 and since the game was starting late I decided to do one table of 12. It was a tight fit but it worked. Luckly I built my new table full size (4' x 8'). We all got to know each other real well

. Once players started dropping it was ok. I'll make sure to be ready for this next game by having both my tables and chips ready just in case.
There is nothing I have ever seen that says you can't do 12. It's just a matter of enough room. It made the game go a bit longer than expected but no one had any complaints.