No I am familiar with hot air rising. But if the pressure existing in the engine bay exceeds the ability of heated air to rise up past the sides of the engine "It ain't happening". Hence I suggested sourcing cooler air from somewhere further forward. As to the bonnet seal who knows, traditionally this area at the base of the windscreen was utilised to force air in. Scuttle venting, reverse bonnet scoops, cowl induction etc. Open the under dash vent in an old Valiant at 60mph (these are connected directly to the plenum at the base of the windscreen) and you'll soon be rid of any loose paper laying round on the floor. Perhaps when idling in Paris the seal's presence may be a hindrance but I think at speed the air flow in this area would actually be trying to push in. Whether it can or not would depend on the pressure present in the engine bay.More HP.