Bud, hard to keep up with the avalanche of answers. Right. No.
On the subject of gluing the bottom fabric:
Leonard said it wasn't necessary, not that you couldn't do it. He works very hard to simplify and keep weight off.
I would do as I feel comfortable with. Glue on the bottom can't weigh much after the solvent or water leaves.
I know some have rib stitched as well. Whatever made them comfortable.
Any billowing is a good reason to ground the aircraft for an inspection. It should not be there. Questions that come to mind:
was the fabric shrunk enough? Has it come unattached? as in glue failure.
Keep in mind these fisheye sports cameras sometimes produce some odd details. look at the last video from Les.
Looks like his top longeron is a rubber hose. Slight movement of the camera makes for some unusual displays.
I wonder what the weight penalty is for rib- stitch and the addition of fabric tapes to cover.
Perhaps someone who has done it can provide some info.
I like Leonards method of using a solvent based glue in two steps, especially the after shrinking step. But I am planning on a water based adhesive so I will need a new plan. Or rethink it.
Tom XL-7
As to where XL-58 is? I think it has had at least three owners.