Anyone converting box truck to rv
 

If anyone is converting box truck to RV I sure would like to pick your brain with a couple of questions that I have one concerning the roof.
My roof looks like thin sheet metal supported by a few ribs running across.
I dont think it could support much weight , and I cant figure out how to go about roof vents.
Has anyone does and could answer a few questions.

How do you plan to insulate your roof, (and walls)? Do you want to be able to walk on the roof? What is your current interior height, and do you want more or less? Do you want roof vents for light or ventilation?

My box is 16ft long by 7'9" wide by 7 ft tall.
I have insulated my side walls with 1 inch rigid foam board I currently have 1 inch of foam board in my roof and I'm planning to add some fiberglass insulation to that.
my roof looks to be thin sheet metal with ribs about 24 inch apart supporting that it definitely does not look strong enough to stand on but I don't know because I would not try it.
What I would really like to do is to be able to cut a hole in the roof for maybe a fantastic fan possibly two but I haven't figured out a way to support a fan with ribs being so far apart also I would like to add a window to the sides but I have the same concerns there I'm afraid by cutting the ribs that I am really compromising the support of the walls I have never done anything like this before so maybe a lot of it is just fear of not knowing how to do it.
My truck is a 2002 Ford E450 with a 16 foot box with barn doors on the back and a 7.3 diesel engine.
and with my roof I would just like to be able to support some solar panels on top and the fans that's really what I want to do with it I'm just curious about whether or not it is strong enough to support it.

Bill

My trailer had 1" angle frames, that screwed to the roof supports anywhere there was wiring for a roof air.

I converted a supreme box. any commercial box is NOT suitable for supporting weight. I doubled the number of roof bows and I still wouldn't walk on it. If you want to box an a/c or vent frame you can add another roof bow alongside and some cross bracing. When I worked on big trucks we used a sheet of plywood on the roof to walk on and make repairs and such.