I just want to make something clear. As part of the group of Third Rail people who has been in discussions with the club to get Yankee Stadium to permit certain items, we were just focused on our sections. If the supporters in sections 235 and 238 wanted to get together with the other members of their section, they could do a tifo. It was never said from the club or Yankee Stadium that they couldn't. The dimensions of the sections were only provided for our 2 sections.
Saying that, Yankee Stadium will still require approval of the message on the tifo and the club personnel will have to bring in the materials into the section and have it waiting there for the supporters.
I hope this helps.