So I did fill the spirals after all,
lazily wisely skipping the areas that will be covered by wraps, and then painted the body white. The instructions recommend flat white, but my preference is to do gloss white and then use a dull clear coat at the end.
You do the engine fairings by gluing them to a piece of BT-20, then cutting them out. It does seem to me it would’ve made this a good deal easier if the fairings had been printed within a rectangle you could just glue as a single piece to the BT-20. Then again, it looks like the instructions are to cut the fairings along their boundary lines, then glue them down, then cut the tubing along the fairing boundary lines. Instead I cut wide, glued, and then cut at the boundaries, and maybe that wasn’t the better way it seemed at first: it meant having to make precise cuts through the thick combination of card stock and tubing, which was a bit difficult.
Next you’re supposed to cut out and remove the orange areas, but only from the card stock, exposing the tubing below. And in hindsight I don’t understand why you wouldn’t cut these areas out before gluing to the tubing. This way, I really wasn’t able to completely remove the card stock but just some layers of it. The bottom layer was securely glued down. I think it’ll be okay though.
A wrap is glued to the S-II/S-IVB adapter, which had just been painted white. Here again I’m kind of puzzled. The white paint isn’t seen, and at least for me it seemed to make the adapter a little too wide for the wrap so needed to be sanded.Next come the body tube wraps. I’m doing one at a time. I did sand the white paint underneath a little to give the glue more to grab on to.
Edit: And you can see in the picture a major screwup. I’d misread the instructions, which say to center the motor hook between the fairing spaces, as saying to center on a fairing space. As soon as I realized that I peeled the wrap off. The glue hadn’t set enough to prevent doing that with little to no visible damage to the wrap. I’ve reglued it correctly.