Regarding "jumper cables," many TC owners will install "jumper cables" permanently in their truck, running directly from under the hood, to their camper batteries, underneath, out of sight, to maximize the charge rate. Minimum 6ga wire, preferably heavier.
It's not 100% but it is better than the factory charging system and will help you extend your batteries on longer trips.
The "smart" charging system in your truck will only ramp down voltage when it senses that the battery is charged. Your camper batteries will keep the system thinking that it is not charged, and will keep the alternator running at the required output to charge the batteries.
