Glue dilution

I like the foamy concept and the many great builds you guys have done. I am looking at the possibility of using some of your techniques on my cargo trailer. Weird huh! Unfortunately, I haven't read enough of the foamy threads to find the information I need. I am looking at insulating the underside of my ct with 2 inch pink foam, then protecting the foam with a layer of canvas with Titebond II. What is the best dilution of the TBII to use on the canvas? How many coats? The size of the area is about 6ft by 13ft. How much coverage is a gallon of TBII ??
I am also debating on putting the canvas directly on the foam panels or doing a canvas overall sheet that is below the foam and runs flat across the ribs. I would think that the canvas on the panels would be more protected and maybe stronger, but the flat undercarriage might help on gas mileage.
So far I only know enough to get myself in trouble.
My other option is to use frp panels across the bottom.
Thoughts anyone.
I am also debating on putting the canvas directly on the foam panels or doing a canvas overall sheet that is below the foam and runs flat across the ribs. I would think that the canvas on the panels would be more protected and maybe stronger, but the flat undercarriage might help on gas mileage.
So far I only know enough to get myself in trouble.

Thoughts anyone.