It’s easy. Down to Thonon then cruise down the side of the lake and through Geneva on satnav (or follow the very clear signage). Take your time and there’s nothing to worry about. There’s a 1 hr pick up spot that basically lets you park at the arrivals gate. Not expensive either.
I did this exact drive a couple of times last summer without any issue. Then drove into the city to drop my wife and 1.5 yr old son off at the airport for the final time and for some reason had a brain fart and took the motorway. Got caught ant the border and was made to pay the annual toll fee. Doh!
And if you want to stop to stretch your legs on the way back stop at Yvoire just before Thonon. It’s beautiful.