Trouble creating bridge in text

I am an extreme novice so bare with me. I'm attempting to prepare a logo for water jet/ plasma cutting and need the negative space in my text to have a bridge to the base material. I've watched a couple tutorials but can't seem to successfully accomplish anything. The attached pictures will show the use of the rectangle tool, followed by selecting the letter with the Pathfinder, and selecting "trim". I will get an error every time stating that I need to select intersecting paths. I thought it might be due to the text being in outline but when I try to fill the text, the negative space is filled as well (another issue?). I'm currently working on the file in DXF format but I tried in eps also. Is the art or initial file just corrupt? I'm assuming that I am just approaching incorrectly.