how is it going to weaken the hull? I am not cutting the hull except to put a hatch in front
Are you really planning to cut a "hatch" in the foredeck? Or is your objective to get air flow through your "cutty"? Solar powered vent may not effect the vessel too much but a hatch could. The deck does add structure to the forward part of your boat. Imagine how the gunnels would flex about if there were no foredeck at all. Cutting a sizable hole will although will have a lesser effect it will have some. It could weaken the boat.
I realize that you have an image of "cruising", overnights in exotic locales. That's all good and a fine dream. But perhaps if you do add a little storage space and a little air through the accommodation space the boom tent isn't so bad.