You don’t need wide trucks for a stable ride, but it’s easier to get a stable ride with wide trucks. Additionally, deep carves are easier to come back from with wide trucks, but takes a bit longer.
I typically run around 14 inches on Surf Rodz. I have a set of Trampa Infinity trucks that I customized the axles on so i can run thane with good bearings, they are 17.5 inches wide. It needs to be said, I’ve only pushed them so far, but they are fun AF.