Omg, good question....well, she would probably call him a pervert constantly and demand that Light leap to her rescue, complaining that L was trying to wedge himself between them. Their bathroom and bedroom sharing would be a total nightmare, and so would them trying to eat together or work together lol.... Honestly I feel like L found her extremely irritating, maybe in a sensory way that made it very difficult for him to focus, so I almost think he would do something extreme like just tie her up again by herself most of the time instead?? He does that to her more than once, calls her stupid constantly, and also tells Light to make her shut up...
I actually never thought about this before, but I think in a way it kind of shows he finds Light much more pleasant to be around. And I don't necessarily mean that in a shippy way, either... Somehow it just feels like L would've had to become a lot more desperate before he would do the 24/7 handcuffs life with Misa than he would with Light.