Bunker in the launchpad?
I've not seen the aftermath of a rocket explosion, how much of the launchpad remains? I presume they are built to withstand an explosion. Why not build a bunker into the launchpad itself, you can stock with medical equipment, food, water, depending on how long it takes to get them out. Or even have an underground access tunnel back to a safe distance/exit. May initially be expensive, but I presume safer than trying to outrun an explosion in any vehicle and almost zero ongoing costs.