Not sure if this will answer your question or not....
but I made my own fitted dipe for DD, and it seems to work just as well if not better than any of the fancy ones I have. It's not as pretty, but inside a wrap, who will ever know?
I took a fitted dipe that fit DD ok, but not perfect, laid it out on a piece of newspaper and traced around it, stretching the elastic as I went, to get an accurate pattern. Then I adjusted it accordingly (made it more narrow through the crotch, longer and wider in the back) and added an extra 1/4 inch or so all the way around for seam allowance.
Then I folded it lengthwise, just to make sure I had both sides the same and cut it out.
I then used the pattern and cut two of the same
Sewed waistband elastic at the top (back) and leg elastic where the leg holes are in the wrong side of one of them, pinned both pieces together, wrong sides out, and stitched them together most of the way around.
Then turned them right side out, attached velcro and stitched up the open spot I used to turn them rightside out.
Very easy! So it doesn't look so great, but works as long as I use a doubler (which I also made myself) in it.
She had it on all night without any leaks last night!!! (with a good cover)
For the prefold, I'd probably take one that works for you, rip the seams out to see how it's put together.
Or just try something, and you can always change your design accordingly.
edited to add: I'd suggest you practice on some old worn out clothes or other source of free fabric first!