Okay, I ended up making a little swatch and trying everything under the sun...even took pix!
I used the knit cast-on method, and will give a few details just in case someone else runs into this.
The swatch had a little section for the Front, then the bound-off Arm section, then a little section for the Back. On WS, you knit across the Front and, when you reach the bound-off stitches, it's time to cast on for the Strap.
Cast on to L needle
This so doesn't work. Your supply yarn spans the Arm opening and closes it up.
Turn work and cast all stitches on to L needle
When you work back through the cast-on stitches, you have to turn your work again to continue working on WS. That puts you back at the beginning of the Strap with nowhere to go.
Turn work, on L needle cast on one stitch, knit that stitch, slip to L needle; cast on next stitch, purl that stitch, slip to L needle; etc.
Bingo. When you're done casting on and making each stitch, turn your work back over and you're at the end of the Strap, ready to stitch around the Back.
Something about this still isn't right because you have to reverse [k1, p1] to [p1, k1] to get everything to line up.
My solution? I just turned and cast on the L needle, turned again and continued around the Back. The straps will have one less row of ribbing...but at this point I'm so not worried about it! :happydance:
HTH someone working on the camisole! Or, if you have a better solution, please post! Renée