Add me to the list of builders with this question. I’m also considering Velcro, but the Velcro must be glued to the shell, and I’d like to preserve the beautiful wood on the interior. Double sided tape and “post it” adhesive sound promising. Adding more adhesive occasionally is not a problem. Let us know if you go this way.
I won’t use the headliner kit for two reasons. I’m omitting the galley, so I’ll line all of the shell with foam including the galley hatch. I also prefer a lighter color. The foam is available online in large sheets in several colors. I’ve seen the gray in the kit, white and a few primary colors. The primary colors are loud, but blue is a possibility. I may use white and paint or stain it, but I have lots of time to decide.