So I have a fleece blanket that measures 36" x ~60" and several yards of 60" wide spandex

I was thinking to make a 2x2 SPE that is is 36" long and has four 18" x ~5" sleeves with a 20" middle section. I was hoping to get two SPEs actually if I could.

My question is: when I sew the spandex to the fleece, do I just sew the sleeves with no extra space for the pad? In other words, is the stretch of the spandex enough to account for the space taken up by the pad?

to use a poor ascii diagram, I'm asking if I should do this:

Code:
F = Fleece
S = Spandex
- = Stitching

-SSSSSSS-
FFFFFFFFF

OR

 SSSSSSSSSS
-S        S-
FFFFFFFFFFFF
Also, I'm guessing a blanket stitch would save me the most material since 5 + 20 + 5 puts me right about

Thanks in advance!