The area sprays that settle onto plants are good for controlling ticks and the like, but mosquitoes will still fly in from outside the treated area to feast. You may be able to obtain (rent?) several
"Mosquito Magnet" type traps and place them strategically near the deck? You'd want to start trapping a week before the party.
Citronella and other "candle" type devices (e.g. the ones with allethrin or
Metofluthrin) will work in still air, but have a limited effective area and are defeated by a light breeze. Also, allethrin, like nearly all pyrethroids, is toxic to cats.
DEET sprays works, but DEET is also pretty nasty stuff, I prefer the sprays with picaridin, avoids that sticky "I just coated myself in
neurotoxic solvent" feeling.
Personally, I want one of Lowell Wood's
lasers.