Think I'd move the stove to the side. Don't know if this would help or if it's possible, but perhaps a downdraft vent that would run under the deck would work so you're not blowing hot greasy air on people's necks.

My parents live in a beach town in a house on pilings and they have a downdraft vent running down under the floor joists and out the side in sort of the same fashion.

if you decide to keep the cooktop in its present l;ocation, a simple trick to get your overhead vent outside would be to runn the duct work from the hood (which would take the place of the microwave, up into the small cabinet above the microwave, up into the soffit. then make a right angle turn towards the windows over the sink, and extend the soffit so it includes the corner over the windows. The soffit is probably empty/fake anyhow. you can then run your vent to an outside wall over one of the corner windows, and vent outside.

Thanks for the suggestions. I am worried that the downdraft vents are not as good as the regular over the range types. I've read conflicting opinions on these forums...The soffit idea might work, although we were hoping to get rid of it altogether in the remodel...the windows over the sink face onto the deck, so it seems to be a tricky problem ! I appreciate any and all possible ideas!

Which way do your joists run in the ceiling? If they are running left to right, run your duct straight up in the ceiling over your range and make a right turn out over your deck. You would need to remove a decent sized hole where the 90 degree turn would go so there would be a little drywall repair. You will need to make sure the space in the joists is clear of pipes etc.

I got rid of my soffit that way and did all the work myself. The only downside is that an 8 inch duct was the largest I could fit as I had pipes in the way. Good luck. I never realized how important ventilation was until I had it, so definitely try to make room for ductwork.