Here is the template as promised & please excuse my crude printing skills
This template is copied from one of the end panels I created for a closet/shelving unit at the foot of our bed in our 25rr.
Some notes
1) I started with a 4X8 1/2 plywood sheet
2) trimmed to 60 1/2"s first then trimmed to 32"s wide
3) the template is approximately 3"s too wide (to allow for fine tuning of the curve
4) do NOT assume both panels are identical
5) measure at least twice & cut once
6) a small combination belt/disc sander helps when shaping the curve for a tight fit with the curve of the wall
7) once the panels are shaped to suit your preferences, measure and trim the panel that sits flush to the wall beside the valance & cut this panel first
8) use the off cut as the measurement to trim the second panel and thus keep the cabinet square
9) the panel closest to the end wall only needs to be sanded on one side and that's why I say to cut the final size of that one first. You can mark on the back side and not worry about having to sand it off
10) I only sanded using 100 grit paper on my palm sander (you may want to go with a finer grit)
11)The valance & blind will need to be removed to install the completed cabinet
The template spacing between lines is 2 1/4"s & the bottom line is 24"s long while the top line will end up @ 15 1/2 long. Once I get back from my work again, I'll measure the total width & then cut & install our shelves (4 or 5)
Hope this is helpful to someone
Here is what the panels look like before being stained