Great drawings...even I understood what you’re saying.
Yes, additional ventilation will help. However, no matter how much outside air you circulate through the attic, the temperature will never be less than the outside air temperature. By increasing air circulation you lower the Air temperature in the attic and thus the “load” on your air conditioning system.
In the tropics and Hawaii (about the same latitude as you) you’ll notice they don’t use air conditioning in lobbies , etc., because it’s too expensive. In stead, they leave whole walls off and let the “trade winds” blow. The temperature of the trade winds is still 90 degrees or so, but increased air movement helps the body “feel” cooler. (That’s why sitting in front of a fan feels good. It’s a matter of having air blowing across the skin...it lowers the “apparent” temperature of the body.)
You can’t rely on trade winds, so you need fans to increase air circulation or pay for air conditioning. (There are other means too. You can google ground air circulation, or geothermal ventilation, etc., They work on the basis that the ground is always about 55 degrees and you can “draw” that air into your house through fans by burying ducts in the ground. Actually, you don’t want that air because it’s musty, but you can use a heat exchanger. It gets complicated and expensive, so most people just pay the local utility.)
Reducing your air conditioning load, you can 1) insure the walls are in shade (that’s why people have large overhangs and they plant shade trees on the south side of there house), 2) increase wall and ceiling insulation, 3) provide thermal pane windows, 4) provide weatherstripping to keep unconditioned air out from heating up conditioned air, and 5) increase ventilation...including the attic, which is your idea.
