I'll figure it out I'm sure.
It's not a common problem for me, heck I only get to take a week off or so every year anyway. That said, I'll poke around at some distance gear. I was wearing shorts and my riding pants which are very loose fitting (I bought them when I was still 270, I'm in the 240's now).
The more I think about it the more I remember that it was the force of my foot pushing on that peg all those miles, lifting my foot helped, but of course I'm not about to do leg lifts while cruising down the road. My abs aren't in that good of shape.
Start with the boots, they're the most constraining - sure I can find something between now and next year when the boss unlocks the cage and lets me out for a bit.