My inner perfectionist took over for a bit last night and the collar and band came off the coat. I trimmed as much off the ends as I could w/o messing with the actual collar, and cut a bias strip of hymo and painstakingly whipped it down to the already graded collar/band seam allowance, then I put the collar assembly back on the coat.
It went in MUCH smoother, and the collar band stands up nicely.
So all I have to do now is catchstitch the inner band/facing seam to the outer band/coat seam and I'll be back to where I was when I got home from work last night.
Maybe I'll get the sleeves in tonight...