I need to admit that I quit cloth.
But, last time I was trying to avoid synthetics with a wiggly toddler, I was looking at Rita's Rump pocket pattern made with flannel or birdseye. Basically, it was a pocket made of cotton...stuff it with your flats or bamboo such or such before approaching the wiggly kid...could even pin the front through all the layers (before putting on) to keep the flats from slipping within. Instead of snaps or velcro, it had really long pointy wings that wrapped around the waist.
Now, last time I googled, I couldn't find it again. Maybe it's been too long, or maybe you'll have better luck. But I think you could improvise by just tracing a pocket diaper with dead elastic and elongating the wings to points.
---------- Post added at 08:29 PM ---------- Previous post was at 08:16 PM ----------
Here it is!
https://www.youtube.com/watch?v=LfrVjViMbP4
http://handmadebyrita.blogspot.com/2...t-pattern.html