Here is a picture of the ACA frame, looking from the inside. Weld points are at the lower right corner, left edge, and top edge. However, you are cutting the fabric away to make the opening anyways, so the additional fabric to remove is not a huge amount. Once you weld the frame in, you wrap the fabric back around the edge and glue it to the inside of the frame. You would have to cut away one spot on the belly and side to weld the lower right corner in this picture to the longeron. However, it is a very small weld, so I think a few inches of fabric would be viable. Not saying it is easy, but I think you could definitely do it with the fabric on.