Hello Bill, Grob,
I'm still a wee bit curious about the loads on the main beam. The tension in the sheet must "go" somewhere. Isn't a.m. tension rather large 6-7* (what you can pull by hand) of maybe 100-200N?
Is this a force so small that it's negligible? I get it to be in the magnitude of 3KN would this be about correct?
Or am I just sailing?

rgds
Patrik Elfving