Hi Larry,
As Brian said, we used 5' x 10' anodized .063 for the roof of our build (we used .040 for the sides) and it was very hard to bend around the galley hatch radius. Of course I found out how to do it easier afterword.

If you are so inclined, find a sheet metal shop with a roller wide enough to pre-bend your aluminum. The rollers will be pitted and will pit your aluminum. So, you buy two sheets of 4' x 8' 1/8" Masonite to sandwich your aluminum protecting it from the rollers. Then have them bend it pretty close to your curve. On our trailer, the front bend was not a problem at all. Only the tight curve on the bottom of the hatch proved to be an issue. I hope this helps.
All the Best,
Dave