Why not put a vent that pushes air from the attic into house

Given that hot air raises, have you considered a Passive Stack Ventilation system. Basically:

• A tall pipe coming out of the top of your loft so the hot air can raise
• You must not have bends in the pipe or it does not work as well
• The topping on the pipe must not add much to the flow resistance
• The sizing of the pipe is important (sorry can’t help on this)
  • Too wide you don’t get fast enough upwards air movement.
  • Not wide enough, you get to much air resistance
• The pipe must come out of the top of the loft and be high enough above the roof
• Soffit venting of some type so the colder air can get in at the bottom

The system will only tent to pull air though the loft when the outside air is colder than the air in the loft (just what you need).

Given the correct conditions and design, a Passive Stack Ventilation system will work forever with no running cost or maintenance. Get anything wrong and it will not work at all.

Also check that your ceilings are well sealed, otherwise all the expensive cold air from your AC will just go up into the loft and be vented out.

For the 50:50 rule, I don't see the ridge vent becoming an intake unless there is another second ridge vent. So given the choice, I'd ignore the 50:50 rule unless your ridge vent is not at a single height.

That said, in your specific situation, with a strong wind from one side and the soffits closed on that side, I think you're creating a situation where regardless of how big the ridge vent is, you could get a down draft from the upwind ridge vent to the downwind soffits. But more importantly, by closing some soffits, you are reducing the airflow under part of the roof. In areas of heavy snow, this airflow is critical to prevent heat from the home from melting snow from the upper part of the roof and having it refreeze on a lower part, forming an ice dam that would backup water into the roof (rot) and possibly into your home (leaks).

Because of the ice dam risk, I think you're better off going with shirlock's earlier suggestion to rely on the Styrofoam tunnels stapled to the rafters and adding some ridge vent filter to any soffits you are worried about. Then install a ridge vent of the proper size for your roof.