After testing my hood with a pressure gauge, showing pressure difference between topside and underside, I actually removed the weatherstripping I had used to seal up the gaps--I'm not sure they're beneficial, as they might actually impede pressure relief of the underhood volume.
Hyundai or Kia air curtain ducts are easily available online, and quite cheap (just a few bucks each). That manufacturer uses them on all models today, so you can find one close to the same curve and distance of your bumper cover (probably something like the Kia Forte or Hyundai Elantra will work best).
You can pattern front wheel strakes off the -2018 Focus (RIP), which uses a tripartite rubber design with good coverage:
