Few glad i checked, Disaster averted, i have got a bit of an overlap on my filler into the cavity (Hopefully not to much that it will cause an issue but well one way to find out). I was gonna tape it directly to the line but will leave a bit of an overlap now so hopefully it will look the part. and yeah I've gone the titebond route seems the easiest to use and the tried and tested route.

Your wooden frame structure seems like a great idea, mine is a broken work table, with a wooden pallet attached to the top with the most impressive box fort you have ever seen as the booth. but the guitar hangs well, has plenty of light, ventilation and protection from wind and its all built in the corner of the garage so i can get a nice sun burn on my legs while working :P