The truck's electrical system can suffer a serious voltage spike if the battery earth is disconnected while the truck is running, because the alternator will still be generating power. This could destroy your ECU.
If you wanted a "kill switch" for the engine, it would also need to include a disconnect of the alternator field wire.
However... if the truck is not running, an earth disconnect will prevent the truck from being started, which is fine and meets your requirements.
In order to do this, ALL of the negative leads from the battery must go though an isolation switch.
Setting up your truck with such an isolation switch can have other benefits too, 2 of those being able to do welding on the truck without physically disconnecting the ECU and if the vehicle will be parked for extended periods, this method will also eliminate all parasitic loads, so your truck start batteries will not go flat as quickly.
Have you ever checked how much current is being drawn from your batteries when the truck is turned off? It's more than you might think.
An isolation switch is not a theoretical concept; it is how my own truck is set up, and it works exceptionally well.
If you want remote functionality for your isolation switch, that is also possible if you use something like the Bluesea ML-RBS Remote Battery Switch.
I should note... if you use one of these switches remotely it will need to be powered, so there will be a very small parasitic power loss in order to do that. If you don't need remote functionality you can use a similar, cheaper switch.