You could leave it all connected and let the solar look after the batteries, but there is a chance the float voltage will be wrong and cause the batteries to lose "water".
First disconnect the array from the controller by taking out the two wires in the controller's "array" terminals. Now you can disconnect the battery bank by removing the wires on the battery posts, including the ones linking the two batteries.
That will prevent the two from interacting while not being on a charger, and will make sure there is no draw on them. On return, hook up the batteries first, then put the two wires back into the controller's array terminals.
Put red tape on all the wires on the pos posts. Take a photo of the battery bank with the wires still on it, so you will put them back on the right posts.
When you get back, bring jumper cables in case the engine battery has run down too far to start the truck. Also, on that, disconnect the 7-pin too if any before leaving.
