Short answer: Why would you? Long answer: There is no real standard or anything for plug-in conversion kits. Any kit you get is basically a crap shoot. There are a few threads around here with people who have successfully fitted a plug-in conversion kit to their third-gen liftbacks but results are mixed at best. The amount of money you invest in the conversion, plus the money you spend on subsequent reliability issues might not even be worth the fuel savings. Being a 2013 you're probably still under your factory hybrid system warranty anyway, why would you throw that away? If you really wanted the space of an MPV but with a plug, you should have gone with a Ford C-Max Energi in my opinion. Perhaps whatever Prius-like crossover (aside from the RAV4 hybrid) that inevitably replaces the v wagon will have a Prime option from the factory.
Unless you really really KNOW what you are doing. VERY risky. If you add another pack with the wrong voltage, it can catch on fire. I notice past plugin conversion companies like Hymotion doesn't exist anymore. The liability for lawsuit would be too great. The good thing is that Toyota is continually improving their battery cells, getting a new pack when it's time is probably a better choice than risking setting your car on fire. In the future I do believe cells will exist that will not catch on fire and provide longer life and capacity. So to me worth the wait not to make such an upgrade attempt due to risk involved. And yes it can be very tempting.
Mitsubishi Outlander has a PHEV option. You will take a huge MPG drop when you are out of electric range. 2018 Mitsubishi Outlander PHEV -Plug-in Hybrid Electric Crossover | Mitsubishi Motors
