BTW you can clean up/true up those long edges of those 3-pieces with the fence-post level, sander technique @OSS1 — Sways member formerly known as McDing — gifted us a long while back. Maybe he can post some photos of his.
Helps make those long foam edges flat and perpendicular. Should help get tighter seams between/among your foam segments/sections. Pull your fence-post-level sander towards you along the full length of the foam segment for each stroke.