Hi there. Apologies if this is covered already, but the word zip is too short for the search function. I have a kind of mid (geartop iirc) which uses an A frame shape with the trekking poles. Consequently the mesh inner sits in the middle and there are two small vestibule areas. The trouble is, there is only an entrance side zip, so accessing the other side is a pain and can only be done from the outside. I'd like to put a zip in the other side so that I can access the vestibule from the inner to use it for storage. I don't need to be able to climb through it. So my questions are, where can I order a suitable lightweight zip (I think a straight line would be fine, the inner is never taut), and is there a good video anywhere of how to sow it in? I won't be doing the sowing, but my wife is pretty handy with a singer.... Any other general advice in this matter is welcome.