I am currently developing a new layout. This must be typeset on a grid, and every line starts at a multiple of 13bp from the top of the text area. To help me check, I'd like to have rules every 13bp from the top of that area on every page without interfering with the typeset text. This is similar to my previous question A package to help with layout generation? Graph paper in the background? where I asked about a grid, but in difference to that question, the grid should start at the top (left) of the text area, not the page.
As far as I see the eso-pic solution is not possible here. What else can I do?
(I am using PDFTeX on Mac and Windows)