I don't think that's feasible. These sensors work by detecting radio waves which propagate near the speed of light. Even if you had two sensors separated by 1 km, they'd both receive the radio signal within ~3 µs of each other. I don't think the sensors guarantee detection time to that level of precision, nor that it's feasible to keep clocks sufficiently synchronized that you can timestamp events at a sub-microsecond level.
With triangulation you only need the clocks accurate enough to correlate the events. This will largely be determined by the rate you see events, and you only need to distinguish specific events if you want to differentiate locations of individual strikes as opposed to a storm front. For a boating case you probably only care about the location of a storm front.
Two sensors measuring angles from a couple dozen meters apart can get you a pretty precise location of storm front especially when aggregating results from multiple detections.
Synchronizing multiple receivers is common. That's how passive ADS-B locators work.[1][2] This works so well there have been attempts to stamp it out.