For me... do you have any idea how hard it is to find a dress shirt cut for a 21" neck that also doesn't involve enough fabric at the waistline to fit two of me? I've got a 51" chest which doesn't help things either.
I'm seriously considering switching to a toga or a kilt.
I found a bias cut dress that fits like a dream. I felt curvy and sexy for the first time in years!
As for you, I vote for the kilt. Kilts...., well, let's say that kilts lead to prurient thoughts.
As for shirts, I recommend buying the right size shirt to fit your neck and then taking it to the tailor's to adjust everything else, especially while your shape changes due to exercise. When your shape stabilizes, you can invest in tailored shirts made specifically for you.
I vote for the kilt, DC...;o]
Most definitely, a kilt! You'll get the most flexibility and comfort with a great-kilt (in Gaelic breacan feile), Braveheart style). This page shows how to wear it. Pay no attention to the "lots of floorspace" note in method 1. I've done it in tents.
Note that the "tail" can be worn just hanging down loose;
wrapped with two lengths, fore and aft, pinned together at the left shoulder (but NOT TO the shoulder);
with a single length (wrapped or not) aft pinned TO the left shoulder (of the vest!);
over the shoulders and closed in front like a cloak if it's cold;
or over the head and shoulders if it's raining.
The small-kilt (feileadh beag or philabeg) won't really solve any problems.