Most well equipped Kinkos type stores or Cad printing services can print C, D, etc sizes. Is that an option for you?
Also try Turbocad (free versions exist) which is Autocad compatible. I choose what standard size C, D, etc. I want to print and all the pages are shown as a tile layout for the source paper I can print (such as 8.5 x 11 paper).
It works very well. I then tape them up. I have results at least 3 feet x 4 feet myself. Larger is possible.
Good luck, Dave