Since the last update, I added the Gatorflex® cover for the piece I cut out of the 3" fore body. This worked great! The thin Gatorflex® has a tough (but brittle) plastic layer and over a sheet of dense foam. It is slightly flexible, which made it perfect for this application. That is, the front of the plate is fairly flat but the back needed to conform to the curve on the main body. I based the rough cut on the section of tube that was cut off and added a little slop to account for changes as I bent the back end to fit. I also trimmed the foam to fit the hole but allowed some overlap of the plastic layer over the tube. It was glued in place with 5-minute epoxy and was held in place with tight wraps of blue masking tape. Once the epoxy was set, I ground the overlap off. Here are two views showing the plate:
I also mentioned that I wanted to add a small tube below the main tube. As I was test fitting various tubes, I ran across some half-oval balsa stock and decided it was just what I was looking for. You can see it in the photos above and here is an head-on shot showing the shape of this component (ignoring the mini-Tabasco container used to hold the front end up):
Finally, I've begun thinking of paint schemes and names. I think I may call it the Tarkus II, after Emerson, Lake and Palmer's 1971 album.