Hi, Toyworks!
Welcome! to the Forum!
Like Danny said, .040" is the minimum recommended for the roof, .032" minimum for the sides (I use .040" all around).
Regarding the galley lid latching ... sometimes the rods have a bit of a hard time lining up with the slots/holes/whatever that they need to catch onto, especially with varying humidity situations. A much simpler way is to use a pair of Draw-type Latches (one on each side of the lid, as close to the bottom as possible) to hold the lid shut (and, because they'r adjustable, they do a great job of pulling the lid in tight if you get a little "spring-back" in the hatch), and then mount a single gate handle near the bottom middle of the lid to lift from.
Danny is also right that I can supply you with a variety of windows (thanks for the plug, Danny ...

...!), and I can also supply you with the door and galley lid latches, galley lid hinge, moldings, lights, and more. Cruise my site -
http://www.LilBear.teardrops.net - and let me know if there is anything I can help you with.
Good Luck on your project, and as always ...
CHEERS!
Celebrating
Retirement after over
32 Years of Building, Promoting, Supporting, Supplying, Living the Lifestyle, and Loving
Teardrop Trailers!"Life Moves a Little Slower When You're On Teardrop Time"The nature of Life, itself, is change ...
"Those who matter, don't mind, and those who mind, don't matter." 