I would like to make a config mod where a prop is attached to a vehicle. My plan would be the propane tank (with permission) to sit inside of stock vehicle. That way, if you crashed, it would explode. Thanks!
So basically you want to spawn two vehicles at once? That's not going to work, I'm afraid. However, if you took the jbeam (and mesh) of the propane tank and included it as an addon part for the covet it could work. But that's a bit more advanced than a config mod and would require some work.