Better fire extinguisher than the Kidde replacement?

For your home, I would recommend looking around while you are in commercial areas. Spot the folks refilling those company's extinguishers. Here, it is Ferguson. They usually have good deals on larger extinguishers, which are better suited for home use. As for the RV, hopefully a small one is enough to help you get everyone out. Fire spreads so quickly in RVs, and creates so many toxic fumes, that if it has spread at all, your best bet is to just get everyone out and away.