Honda generator enclosure fan question

I did follow the link and it is greatly appreciated. HE shows the mixed exhaust temperature at 190°, I have no way to measure exhaust and then He gives temperatures inside the box. I was looking for actual case temperature of the Honda This is the humble beginnings not the end product. It may not show in the picture But I am separating the engine exhaust from the cooling air exhaust to have a future venturi type exhaust riser. Mine will be mounted on the camper, not portable. I am also adding the fans, if I do not have to use them would be ok!

At the moment I am experimenting with card board templates to make sure I have enough area for free air flow. One thing I have noticed is the box gets fairly hot on the bottom, which seems really odd?

Great ideas and truly appreciated the input! Jim