You can create a printer file with a width greater than 255 (378 is the actual limit - see the PAGWIDTH parameter in the STRRLU command). The problem is that you can't have any fields that begin at a position greater than 255.
When I last did it, I created text fields starting before position 255 that extended the remaining width of the printer file. Then I used a combination of %subst(), %editc(), %editw(), and evalr to format the information in the text fields. It's a pain to make changes, but it does work.